Carrier switching method, base station, and user equipment

ABSTRACT

The present invention discloses a carrier switching method, a base station, and user equipment, where the method includes: determining, according to carrier switching capability information of user equipment UE, a carrier switching policy according to which the UE performs carrier switching; and sending carrier switching indication information to the UE, where the carrier switching indication information is used for indicating the carrier switching policy, so that the UE performs carrier switching according to the carrier switching policy. In the carrier switching method, the base station and the user equipment according to embodiments of the present invention, the UE having no carrier aggregation capability is enabled to dynamically perform switching between at least two carriers, so that quality of service of a service of the UE can be improved, user experience can be improved, and system performance can be improved.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/979,390, filed on Dec. 27, 2015, which is a continuation ofInternational Patent Application No. PCT/CN2013/078194, filed on Jun.27, 2013. All of the aforementioned applications are hereby incorporatedby reference in their entireties.

TECHNICAL FIELD

Embodiments of the present invention relate to the field ofcommunications, and in particular, to a carrier switching method, a basestation, and user equipment.

BACKGROUND

In the 3rd generation partnership project (3GPP), a carrier aggregation(CA) technology is introduced, so that user equipment (UE) supportingthe carrier aggregation technology can send or receive data on more thanone component carrier within one transmission time interval, therebyimproving a peak rate of the user equipment. In a case of carrieraggregation, multiple pairs of system-associated carriers may beincluded, where a pair of system-associated carriers denote paireddownlink and uplink carriers, that is, carriers corresponding tosignaling connection and notification in a system information block 2(SIB2), and may be considered as a serving cell, the downlink carrier ofthe system-associated carriers may be considered as a downlink carriercorresponding to the serving cell, and the uplink carrier of thesystem-associated carriers may be considered as an uplink carriercorresponding to the serving cell. However, some UEs having no carrieraggregation capability also exist in a system, and this type of UEscannot receive and/or send data on more than one carrier at a samemoment, where having no carrier aggregation capability includes: havingno carrier aggregation capability on a downlink, having no carrieraggregation capability on an uplink, or having no carrier aggregationcapability on both an uplink and a downlink.

On each serving cell and a carrier corresponding to the serving cell, aquantity of user equipment and service distribution are time-variant tosome extent, and channel quality of user equipment on each serving celland a carrier corresponding to the serving cell is also time-variant.After being connected to a base station, user equipment having nocarrier aggregation capability can operate only on a time divisionduplex (TDD) carrier or a pair of system-associated frequency divisionduplex (FDD) carriers; therefore, channel quality of the user equipmentis also affected by a load of this carrier or carrier pair and oftenchanges, causing relatively bad user experience. The present inventionprovides a carrier switching method, so that user equipment having nocarrier aggregation capability can dynamically perform switching betweencarriers and perform data transmission between the carriers, so as tobetter match service distribution and dynamic change of channel qualitywithin each carrier, thereby obtaining better system performance anduser experience.

SUMMARY

Embodiments of the present invention provide a carrier switching method,a base station, and user equipment, and can enable user equipment havingno carrier aggregation capability to dynamically perform switchingbetween carriers and perform data transmission between the carriers.

According to a first aspect, a carrier switching method is provided,including: determining, according to carrier switching capabilityinformation of user equipment UE, a carrier switching policy accordingto which the UE performs carrier switching; and sending carrierswitching indication information to the UE, where the carrier switchingindication information is used for indicating the carrier switchingpolicy, so that the UE performs carrier switching according to thecarrier switching policy.

With reference to the first aspect, in a first possible implementationmanner, the determining, according to carrier switching capabilityinformation of UE, a carrier switching policy according to which the UEperforms carrier switching includes: determining, according to thecarrier switching capability information of the UE and current networkstatus information, the carrier switching policy according to which theUE performs carrier switching.

With reference to the first aspect or with reference to the firstpossible implementation manner of the first aspect, in a second possibleimplementation manner, the carrier switching policy includes completingcarrier switching from a current downlink carrier to a target downlinkcarrier in an M1^(th) subframe after a current subframe in which thecarrier switching indication information is sent to the UE, where M1 isan integer greater than or equal to 1.

With reference to the first aspect or with reference to the first orsecond possible implementation manner of the first aspect, in a thirdpossible implementation manner, the carrier switching policy includescompleting carrier switching from a current uplink carrier to a targetuplink carrier in an M2^(th) subframe after the current subframe inwhich the carrier switching indication information is sent to the UE,where M2 is an integer greater than or equal to 1.

With reference to the third possible implementation manner of the firstaspect, in a fourth possible implementation manner, when the currentdownlink carrier and the current uplink carrier in the carrier switchingpolicy are system-associated carriers, and the target downlink carrierand the target uplink carrier to which the UE performs carrier switchingare system-associated carriers, a time needed to switch the UE from thecurrent downlink carrier to the target downlink carrier is equal to atime needed to switch the UE from the current uplink carrier to thetarget uplink carrier.

With reference to the first aspect or with reference to any possibleimplementation manner of the first to the fourth possible implementationmanners of the first aspect, in a fifth possible implementation manner,the carrier switching indication information is carried in downlinkcontrol information DCI, where the DCI is further used for instructingthe UE to receive downlink data on the current downlink carrier; or thecarrier switching indication information is carried in DCI, where theDCI is further used for instructing the UE to send uplink data on thecurrent uplink carrier or on the target uplink carrier to which carrierswitching is performed; or the carrier switching indication informationis carried in DCI, where the DCI is used for instructing the UE toperform carrier switching according to the carrier switching policy andis not used for data scheduling.

With reference to the fifth possible implementation manner of the firstaspect, in a sixth possible implementation manner, a carrier indicatorfield CIF included in the DCI is used for carrying the carrier switchingindication information.

With reference to the fifth possible implementation manner of the firstaspect, in a seventh possible implementation manner, the DCI isscrambled by using a cell identifier corresponding to a target carrier,so as to instruct the UE to switch from a current carrier to the targetcarrier; or the DCI instructs the UE to feed back channel stateinformation of the target downlink carrier, so as to instruct the UE toswitch from the current downlink carrier to the target downlink carrier.

With reference to the first aspect or with reference to any possibleimplementation manner of the first to the seventh possibleimplementation manners of the first aspect, in an eighth possibleimplementation manner, before the determining, according to carrierswitching capability information of UE, a carrier switching policyaccording to which the UE performs carrier switching, the method furtherincludes: determining a primary-component-carrier subframe pattern ofthe UE, where the primary-component-carrier subframe pattern is used forinstructing the UE to communicate with a base station in a firstsubframe by using a primary component carrier of the UE; and thedetermining, according to carrier switching capability information ofUE, a carrier switching policy according to which the UE performscarrier switching includes: determining the carrier switching policy ofthe UE according to the carrier switching capability information of theUE and the primary-component-carrier subframe pattern.

With reference to the first aspect or with reference to the firstpossible implementation manner of the first aspect, in a ninth possibleimplementation manner, the carrier switching policy includes carriersubframe patterns of at least two carriers, a carrier subframe patternof each carrier of the at least two carriers is separately used forindicating a reserved subframe in which the UE communicates with a basestation by using the carrier, and the carrier subframe patterns of thecarriers are not completely overlapped.

With reference to the ninth possible implementation manner of the firstaspect, in a tenth possible implementation manner, a first subframeratio in the at least two carriers is a reciprocal of a second subframeratio, the first subframe ratio is a ratio between a quantity ofreserved subframes of a first uplink carrier and a quantity of reservedsubframes of a first downlink carrier, where the first uplink carrierand the first downlink carrier of the at least two carriers aresystem-associated, and a relative relationship between a location of areserved subframe of the first uplink carrier and a location of areserved subframe of the first downlink carrier satisfies a preset firstTDD ratio configuration, where the second subframe ratio is a ratiobetween a quantity of reserved subframes of a second uplink carrier anda quantity of reserved subframes of a second downlink carrier, where thesecond uplink carrier and the second downlink carrier of the at leasttwo carriers are system-associated; or a ratio between subframes of acarrier subframe pattern of a third downlink carrier and subframes of acarrier subframe pattern of a fourth downlink carrier of the at leasttwo carriers is a first TDD configuration of seven preset time divisionmultiplexing TDD configurations, where the carrier subframe pattern ofthe third downlink carrier corresponds to downlink and special subframesof the first TDD configuration, and the carrier subframe pattern of thefourth downlink carrier corresponds to an uplink subframe of the firstTDD configuration.

With reference to the first aspect or with reference to any possibleimplementation manner of the first to the tenth possible implementationmanners of the first aspect, in an eleventh possible implementationmanner, before the determining, according to carrier switchingcapability information of UE, a carrier switching policy according towhich the UE performs carrier switching, the method further includes:receiving the carrier switching capability information of the UE that issent by the UE.

With reference to the first aspect or with reference to any possibleimplementation manner of the first to the eleventh possibleimplementation manners of the first aspect, in a twelfth possibleimplementation manner, the carrier switching capability information ofthe UE includes at least one piece of the following information:information about a quantity of carriers supported by the UE,information about a carrier frequency band supported by the UE andinformation about a carrier switching type supported by the UE.

With reference to the first aspect or with reference to any possibleimplementation manner of the first to the twelfth possibleimplementation manners of the first aspect, in a thirteenth possibleimplementation manner, before the determining, according to carrierswitching capability information of UE, a carrier switching policyaccording to which the UE performs carrier switching, the method furtherincludes: sending first indication information to the UE, where thefirst indication information is used for indicating a candidate carrierset according to which the UE performs carrier switching and/or aswitching time delay for which the UE performs carrier switching.

According to a second aspect, a carrier switching method is provided,including: receiving carrier switching indication information sent by abase station, where the carrier switching indication information is usedfor indicating a carrier switching policy according to which userequipment UE performs carrier switching; and performing carrierswitching according to the carrier switching policy indicated in thecarrier switching indication information.

With reference to the second aspect, in a first possible implementationmanner, the carrier switching policy includes completing carrierswitching from a current downlink carrier to a target downlink carrierin an M1^(th) subframe after a current subframe in which the carrierswitching indication information sent by the base station is received,where M1 is an integer greater than or equal to 1.

With reference to the second aspect or with reference to the firstpossible implementation manner of the second aspect, in a secondpossible implementation manner, the carrier switching policy includescompleting carrier switching from a current uplink carrier to a targetuplink carrier in an M2^(th) subframe after the current subframe inwhich the carrier switching indication information sent by the basestation is received, where M2 is an integer greater than or equal to 1.

With reference to the second possible implementation manner of thesecond aspect, in a third possible implementation manner, when thecurrent downlink carrier and the current uplink carrier in the carrierswitching policy are system-associated carriers, and the target downlinkcarrier and the target uplink carrier to which the UE performs carrierswitching are system-associated carriers, a time needed to switch the UEfrom the current downlink carrier to the target downlink carrier isequal to a time needed to switch the UE from the current uplink carrierto the target uplink carrier.

With reference to the second aspect or with reference to any possibleimplementation manner of the first to the third possible implementationmanners of the second aspect, in a fourth possible implementationmanner, the carrier switching indication information is carried indownlink control information DCI, where the DCI is further used forinstructing the UE to receive downlink data on the current downlinkcarrier; or the carrier switching indication information is carried inDCI, where the DCI is further used for instructing the UE to send uplinkdata on the current uplink carrier or on the target uplink carrier towhich carrier switching is performed; or the carrier switchingindication information is carried in DCI, where the DCI is used forinstructing the UE to perform carrier switching according to the carrierswitching policy and is not used for data scheduling.

With reference to the fourth possible implementation manner of thesecond aspect, in a fifth possible implementation manner, a carrierindicator field CIF included in the DCI is used for carrying the carrierswitching indication information.

With reference to the fourth possible implementation manner of thesecond aspect, in a sixth possible implementation manner, the DCI isscrambled by using a cell identifier corresponding to a target carrier,so as to instruct the UE to switch from a current carrier to the targetcarrier; or the DCI instructs the UE to feed back channel stateinformation of the target downlink carrier, so as to instruct the UE toswitch from the current downlink carrier to the target downlink carrier.

With reference to the second aspect or with reference to any possibleimplementation manner of the first to the sixth possible implementationmanners of the second aspect, in a seventh possible implementationmanner, before the performing carrier switching according to the carrierswitching policy indicated in the carrier switching indicationinformation, the method further includes: determining aprimary-component-carrier subframe pattern of the UE, where theprimary-component-carrier subframe pattern is used for instructing theUE to communicate with the base station in a first subframe by using aprimary component carrier of the UE; and the performing carrierswitching according to the carrier switching policy indicated in thecarrier switching indication information includes: performing carrierswitching according to the carrier switching policy and theprimary-component-carrier subframe pattern.

With reference to the second aspect or with reference to the firstpossible implementation manner of the second aspect, in an eighthpossible implementation manner, the carrier switching policy includescarrier subframe patterns of at least two carriers, a carrier subframepattern of each carrier of the at least two carriers is separately usedfor indicating a reserved subframe in which the UE communicates with abase station by using the carrier, and the carrier subframe patterns ofthe carriers are not completely overlapped.

With reference to the eighth possible implementation manner of thesecond aspect, in a ninth possible implementation manner, a firstsubframe ratio in the at least two carriers is a reciprocal of a secondsubframe ratio, the first subframe ratio is a ratio between a quantityof reserved subframes of a first uplink carrier and a quantity ofreserved subframes of a first downlink carrier, where the first uplinkcarrier and the first downlink carrier of the at least two carriers aresystem-associated, and a relative relationship between a location of areserved subframe of the first uplink carrier and a location of areserved subframe of the first downlink carrier satisfies a preset firstTDD ratio configuration, where the second subframe ratio is a ratiobetween a quantity of reserved subframes of a second uplink carrier anda quantity of reserved subframes of a second downlink carrier, where thesecond uplink carrier and the second downlink carrier of the at leasttwo carriers are system-associated; or a ratio between subframes of acarrier subframe pattern of a third downlink carrier and subframes of acarrier subframe pattern of a fourth downlink carrier of the at leasttwo carriers is a first TDD configuration of seven preset time divisionmultiplexing TDD configurations, where the carrier subframe pattern ofthe third downlink carrier corresponds to downlink and special subframesof the first TDD configuration, and the carrier subframe pattern of thefourth downlink carrier corresponds to an uplink subframe of the firstTDD configuration.

With reference to the second aspect or with reference to any possibleimplementation manner of the first to the ninth possible implementationmanners of the second aspect, in a tenth possible implementation manner,before the receiving carrier switching indication information sent by abase station, the method further includes: sending carrier switchingcapability information of the UE to the base station, so that the basestation determines the carrier switching policy according to the carrierswitching capability information.

With reference to the second aspect or with reference to any possibleimplementation manner of the first to the tenth possible implementationmanners of the second aspect, in an eleventh possible implementationmanner, the carrier switching capability information of the UE includesat least one piece of the following information: information about aquantity of carriers supported by the UE, information about a carrierfrequency band supported by the UE and information about a carrierswitching type supported by the UE.

With reference to the second aspect or with reference to any possibleimplementation manner of the first to the eleventh possibleimplementation manners of the second aspect, in a twelfth possibleimplementation manner, before the receiving carrier switching indicationinformation sent by a base station, the method further includes:receiving first indication information sent by the base station, wherethe first indication information is used for indicating a candidatecarrier set according to which the UE performs carrier switching and/ora switching time delay for which the UE performs carrier switching.

According to a third aspect, a base station is provided, where the basestation includes: a determining module, configured to determine,according to carrier switching capability information of user equipmentUE, a carrier switching policy according to which the UE performscarrier switching; and a sending module, configured to send carrierswitching indication information to the UE, where the carrier switchingindication information is used for indicating the carrier switchingpolicy determined by the determining module, so that the UE performscarrier switching according to the carrier switching policy.

With reference to the third aspect, in a first possible implementationmanner, the determining module is specifically configured to determine,according to the carrier switching capability information of the UE andcurrent network status information, the carrier switching policyaccording to which the UE performs carrier switching.

With reference to the third aspect or with reference to the firstpossible implementation manner of the third aspect, in a second possibleimplementation manner, the carrier switching policy determined by thedetermining module includes completing carrier switching from a currentdownlink carrier to a target downlink carrier in an M1^(th) subframeafter a current subframe in which the carrier switching indicationinformation is sent to the UE, where M1 is an integer greater than orequal to 1.

With reference to the third aspect or with reference to the first orsecond possible implementation manner of the third aspect, in a thirdpossible implementation manner, the carrier switching policy determinedby the determining module includes completing carrier switching from acurrent uplink carrier to a target uplink carrier in an M2^(th) subframeafter the current subframe in which the carrier switching indicationinformation is sent to the UE, where M2 is an integer greater than orequal to 1.

With reference to the third possible implementation manner of the thirdaspect, in a fourth possible implementation manner, when the currentdownlink carrier and the current uplink carrier in the carrier switchingpolicy are system-associated carriers, and the target downlink carrierand the target uplink carrier to which the UE performs carrier switchingare system-associated carriers, a time needed to switch the UE from thecurrent downlink carrier to the target downlink carrier is equal to atime needed to switch the UE from the current uplink carrier to thetarget uplink carrier.

With reference to the third aspect or with reference to any possibleimplementation manner of the first to the fourth possible implementationmanners of the third aspect, in a fifth possible implementation manner,the sending module is specifically configured to send downlink controlinformation DCI carrying the carrier switching indication information,where the DCI is further used for instructing the UE to receive downlinkdata on the current downlink carrier; or the sending module isspecifically configured to send DCI carrying the carrier switchingindication information, where the DCI is further used for instructingthe UE to send uplink data on the current uplink carrier or on thetarget uplink carrier to which carrier switching is performed; or thesending module is specifically configured to send DCI carrying thecarrier switching indication information, where the DCI is used forinstructing the UE to perform carrier switching according to the carrierswitching policy and is not used for data scheduling.

With reference to the fifth possible implementation manner of the thirdaspect, in a sixth possible implementation manner, a carrier indicatorfield CIF included in the DCI sent by the sending module is used forcarrying the carrier switching indication information.

With reference to the fifth possible implementation manner of the thirdaspect, in a seventh possible implementation manner, the DCI sent by thesending module is scrambled by using a cell identifier corresponding toa target carrier, so as to instruct the UE to switch from a currentcarrier to the target carrier; or the DCI sent by the sending moduleinstructs the UE to feed back channel state information of the targetdownlink carrier, so as to instruct the UE to switch from the currentdownlink carrier to the target downlink carrier.

With reference to the third aspect or with reference to any possibleimplementation manner of the first to the seventh possibleimplementation manners of the third aspect, in an eighth possibleimplementation manner, the determining module is further configured to:before the carrier switching policy according to which the UE performscarrier switching is determined according to the carrier switchingcapability information of the UE, determine a primary-component-carriersubframe pattern of the UE, where the primary-component-carrier subframepattern is used for instructing the UE to communicate with the basestation in a first subframe by using a primary component carrier of theUE; and determine the carrier switching policy of the UE according tothe carrier switching capability information of the UE and theprimary-component-carrier subframe pattern.

With reference to the third aspect or with reference to the firstpossible implementation manner of the third aspect, in a ninth possibleimplementation manner, the carrier switching policy includes carriersubframe patterns of at least two carriers, a carrier subframe patternof each carrier of the at least two carriers is separately used forindicating a reserved subframe in which the UE communicates with a basestation by using the carrier, and the carrier subframe patterns of thecarriers are not completely overlapped.

With reference to the ninth possible implementation manner of the thirdaspect, in a tenth possible implementation manner, a first subframeratio in the at least two carriers is a reciprocal of a second subframeratio, the first subframe ratio is a ratio between a quantity ofreserved subframes of a first uplink carrier and a quantity of reservedsubframes of a first downlink carrier, where the first uplink carrierand the first downlink carrier of the at least two carriers aresystem-associated, and a relative relationship between a location of areserved subframe of the first uplink carrier and a location of areserved subframe of the first downlink carrier satisfies a preset firstTDD ratio configuration, where the second subframe ratio is a ratiobetween a quantity of reserved subframes of a second uplink carrier anda quantity of reserved subframes of a second downlink carrier, where thesecond uplink carrier and the second downlink carrier of the at leasttwo carriers are system-associated; or a ratio between subframes of acarrier subframe pattern of a third downlink carrier and subframes of acarrier subframe pattern of a fourth downlink carrier of the at leasttwo carriers is a first TDD configuration of seven preset time divisionmultiplexing TDD configurations, where the carrier subframe pattern ofthe third downlink carrier corresponds to downlink and special subframesof the first TDD configuration, and the carrier subframe pattern of thefourth downlink carrier corresponds to an uplink subframe of the firstTDD configuration.

With reference to the third aspect or with reference to any possibleimplementation manner of the first to the tenth possible implementationmanners of the third aspect, in an eleventh possible implementationmanner, the base station further includes: a receiving module,configured to: before the determining module determines, according tothe carrier switching capability information of the UE, the carrierswitching policy according to which the UE performs carrier switching,receive the carrier switching capability information of the UE that issent by the UE.

With reference to the third aspect or with reference to any possibleimplementation manner of the first to the eleventh possibleimplementation manners of the third aspect, in a twelfth possibleimplementation manner, the carrier switching capability information ofthe UE includes at least one piece of the following information:information about a quantity of carriers supported by the UE,information about a carrier frequency band supported by the UE andinformation about a carrier switching type supported by the UE.

With reference to the third aspect or with reference to any possibleimplementation manner of the first to the twelfth possibleimplementation manners of the third aspect, in a thirteenth possibleimplementation manner, the sending module is further configured to:before the determining module determines, according to the carrierswitching capability information of the UE, the carrier switching policyaccording to which the UE performs carrier switching, send firstindication information to the UE, where the first indication informationis used for indicating a candidate carrier set according to which the UEperforms carrier switching and/or a switching time delay for which theUE performs carrier switching.

According to a fourth aspect, user equipment UE is provided, including:a receiving module, configured to receive carrier switching indicationinformation sent by a base station, where the carrier switchingindication information is used for indicating a carrier switching policyaccording to which the user equipment UE performs carrier switching; anda carrier switching module, configured to perform carrier switchingaccording to the carrier switching policy indicated in the carrierswitching indication information received by the receiving module.

With reference to the fourth aspect, in a first possible implementationmanner, the carrier switching policy includes completing carrierswitching from a current downlink carrier to a target downlink carrierin an M1^(th) subframe after a current subframe in which the carrierswitching indication information sent by the base station is received,where M1 is an integer greater than or equal to 1.

With reference to the fourth aspect or with reference to the firstpossible implementation manner of the fourth aspect, in a secondpossible implementation manner, the carrier switching policy includescompleting carrier switching from a current uplink carrier to a targetuplink carrier in an M2^(th) subframe after the current subframe inwhich the carrier switching indication information sent by the basestation is received, where M2 is an integer greater than or equal to 1.

With reference to the second possible implementation manner of thefourth aspect, in a third possible implementation manner, when thecurrent downlink carrier and the current uplink carrier in the carrierswitching policy are system-associated carriers, and the target downlinkcarrier and the target uplink carrier to which the UE performs carrierswitching are system-associated carriers, a time needed to switch the UEfrom the current downlink carrier to the target downlink carrier isequal to a time needed to switch the UE from the current uplink carrierto the target uplink carrier.

With reference to the fourth aspect or with reference to any possibleimplementation manner of the first to the third possible implementationmanners of the fourth aspect, in a fourth possible implementationmanner, the carrier switching indication information received by thereceiving module is carried in downlink control information DCI, wherethe DCI is further used for instructing the UE to receive downlink dataon the current downlink carrier; or the carrier switching indicationinformation received by the receiving module is carried in DCI, wherethe DCI is further used for instructing the UE to send uplink data onthe current uplink carrier or on the target uplink carrier to whichcarrier switching is performed; or the carrier switching indicationinformation received by the receiving module is carried in DCI, wherethe DCI is used for instructing the UE to perform carrier switchingaccording to the carrier switching policy and is not used for datascheduling.

With reference to the fourth possible implementation manner of thefourth aspect, in a fifth possible implementation manner, a carrierindicator field CIF included in the DCI is used for carrying the carrierswitching indication information.

With reference to the fourth possible implementation manner of thefourth aspect, in a sixth possible implementation manner, the DCI isscrambled by using a cell identifier corresponding to a target carrier,so as to instruct the UE to switch from a current carrier to the targetcarrier; or the DCI instructs the UE to feed back channel stateinformation of the target downlink carrier, so as to instruct the UE toswitch from the current downlink carrier to the target downlink carrier.

With reference to the fourth aspect or with reference to any possibleimplementation manner of the first to the sixth possible implementationmanners of the fourth aspect, in a seventh possible implementationmanner, the UE further includes: a determining module, configured to:before the carrier switching module performs carrier switching accordingto the carrier switching policy, determine a primary-component-carriersubframe pattern of the UE, where the primary-component-carrier subframepattern is used for instructing the UE to communicate with the basestation in a first subframe by using a primary component carrier of theUE; and the carrier switching module is specifically configured toperform carrier switching according to the carrier switching policyreceived by the receiving module and the primary-component-carriersubframe pattern determined by the determining module.

With reference to the fourth aspect or with reference to the firstpossible implementation manner of the fourth aspect, in an eighthpossible implementation manner, the carrier switching policy includescarrier subframe patterns of at least two carriers, a carrier subframepattern of each carrier of the at least two carriers is separately usedfor indicating a reserved subframe in which the UE communicates with abase station by using the carrier, and the carrier subframe patterns ofthe carriers are not completely overlapped.

With reference to the eighth possible implementation manner of thefourth aspect, in a ninth possible implementation manner, a firstsubframe ratio in the at least two carriers is a reciprocal of a secondsubframe ratio, the first subframe ratio is a ratio between a quantityof reserved subframes of a first uplink carrier and a quantity ofreserved subframes of a first downlink carrier, where the first uplinkcarrier and the first downlink carrier of the at least two carriers aresystem-associated, and a relative relationship between a location of areserved subframe of the first uplink carrier and a location of areserved subframe of the first downlink carrier satisfies a preset firstTDD ratio configuration, where the second subframe ratio is a ratiobetween a quantity of reserved subframes of a second uplink carrier anda quantity of reserved subframes of a second downlink carrier, where thesecond uplink carrier and the second downlink carrier of the at leasttwo carriers are system-associated; or a ratio between subframes of acarrier subframe pattern of a third downlink carrier and subframes of acarrier subframe pattern of a fourth downlink carrier of the at leasttwo carriers is a first TDD configuration of seven preset time divisionmultiplexing TDD configurations, where the carrier subframe pattern ofthe third downlink carrier corresponds to downlink and special subframesof the first TDD configuration, and the carrier subframe pattern of thefourth downlink carrier corresponds to an uplink subframe of the firstTDD configuration.

With reference to the fourth aspect or with reference to any possibleimplementation manner of the first to the ninth possible implementationmanners of the fourth aspect, in a tenth possible implementation manner,the UE further includes: a sending module, configured to: before thereceiving module receives the carrier switching indication informationsent by the base station, send carrier switching capability informationof the UE to the base station, so that the base station determines thecarrier switching policy according to the carrier switching capabilityinformation.

With reference to the fourth aspect or with reference to any possibleimplementation manner of the first to the tenth possible implementationmanners of the fourth aspect, in an eleventh possible implementationmanner, the carrier switching capability information of the UE includesat least one piece of the following information: information about aquantity of carriers supported by the UE, information about a carrierfrequency band supported by the UE and information about a carrierswitching type supported by the UE.

With reference to the fourth aspect or with reference to any possibleimplementation manner of the first to the eleventh possibleimplementation manners of the fourth aspect, in a twelfth possibleimplementation manner, the receiving module is further configured to:before the carrier switching indication information sent by the basestation is received, receive first indication information sent by thebase station, where the first indication information is used forindicating a candidate carrier set according to which the UE performscarrier switching and/or a switching time delay for which the UEperforms carrier switching.

Based on the foregoing technical solutions, in a carrier switchingmethod, a base station, and user equipment provided in the embodimentsof the present invention, the UE having no carrier aggregationcapability is enabled to dynamically perform switching between at leasttwo carriers, so that quality of service of a service of the UE can beimproved, user experience can be improved, and system performance can beimproved.

BRIEF DESCRIPTION OF THE DRAWINGS

To describe the technical solutions in the embodiments of the presentinvention more clearly, the following briefly introduces theaccompanying drawings required for describing the embodiments of thepresent invention. The accompanying drawings in the followingdescription show merely some embodiments of the present invention, and aperson of ordinary skill in the art may still derive other drawings fromthese accompanying drawings without creative efforts.

FIG. 1 is a schematic flowchart of a carrier switching method accordingto an embodiment of the present invention;

FIG. 2 is a schematic diagram in which a needed time of uplink carrierswitching is equal to that of downlink carrier switching in a carrierswitching policy according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a first carrier subframe patternaccording to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a second carrier subframe patternaccording to an embodiment of the present invention;

FIG. 5 is a schematic flowchart of a carrier switching method accordingto another embodiment of the present invention;

FIG. 6 is a schematic block diagram of a base station according to anembodiment of the present invention;

FIG. 7 is a schematic block diagram of user equipment according to anembodiment of the present invention;

FIG. 8 is a schematic block diagram of a base station according toanother embodiment of the present invention; and

FIG. 9 is a schematic block diagram of user equipment according toanother embodiment of the present invention.

DETAILED DESCRIPTION

The following clearly describes the technical solutions in theembodiments of the present invention with reference to the accompanyingdrawings in the embodiments of the present invention. Apparently, thedescribed embodiments are some but not all of the embodiments of thepresent invention. All other embodiments obtained by a person ofordinary skill in the art based on the embodiments of the presentinvention without creative efforts shall fall within the protectionscope of the present invention.

It should be understood that, the technical solutions of the embodimentsof the present invention may be applied to various communicationssystems, such as: a global system for mobile communications (GSM)system, a code division multiple access (CDMA) system, a wideband codedivision multiple access (WCDMA) system, a general packet radio service(GPRS), a long term evolution (LTE) system, an LTE frequency divisionduplex (FDD) system, an LTE time division duplex (TDD) system, auniversal mobile telecommunications system (UMTS), a worldwideinteroperability for microwave access (WiMAX) communications system orthe like.

It should also be understood that in the embodiments of the presentinvention, user equipment (UE) may be referred to as a terminal, amobile station (MS), a mobile terminal, and the like. The user equipmentmay communicate with one or more core networks through a radio accessnetwork (RAN). For example, the user equipment may be a mobile phone(also referred to as a “cellular” phone) or a computer with a mobileterminal. For example, the user equipment may also be a portable,pocket-sized, handheld, computer built-in, or in-vehicle mobileapparatus, which exchanges voice and/or data with the radio accessnetwork.

It should be further understood that, in the embodiments of the presentinvention, a base station may be a base station (BTS) in the GSM orCDMA, and may also be a base station ((NodeB) in the WCDMA, and mayfurther be an evolved NodeB (eNB or e-NodeB) in the LTE. The presentinvention constitutes no limitation thereto.

It should be further understood that, a carrier switching methodprovided in the embodiments of the present invention is applicable to afrequency division duplex (FDD) system, a time division duplex (TDD)system, and a hybrid system of frequency division duplex FDD and timedivision duplex TDD. For convenience of description, an example in whichthe carrier switching method provided in the embodiments of the presentinvention is applied to the FDD system is used for performingdescription below, but the embodiments of the present invention are notlimited thereto.

It should be further understood that, the embodiments of the presentinvention are applicable to UE having no carrier aggregation capability,and the UE may perform switching between at least two carriers, wherethe at least two carriers may be at least two co-site carriers of a samebase station, or at least two carriers of a macro cell and a micro cellof ideal backhaul, or at least two carriers of a macro cell and a microcell having non-ideal backhaul, but the embodiments of the presentinvention are not limited thereto. Moreover, in the embodiments of thepresent invention, when it is not particularly described whether acarrier is an uplink carrier or a downlink carrier, the carrier mayrefer to an uplink carrier, or may refer to a downlink carrier.Similarly, if there is no particular description, a current carrier mayrefer to a current uplink carrier or a current downlink carrier, and atarget carrier may refer to a target uplink carrier or a target downlinkcarrier. Additionally, a primary component carrier of UE refers to acarrier used for keeping coverage and a radio resource control (RRC)connection; a secondary component carrier of the UE refers to a carrier,mainly used for transmitting data, on which radio link monitoring andradio link failure determining on an RRC connection do not rely, and UEmay have a primary component carrier and at least one secondarycomponent carrier. If there is no particular description, a carrier maybe a primary component carrier, or may be a secondary component carrier.If there is no particular description, a primary component carrier maybe an uplink primary component carrier, or may be a downlink primarycomponent carrier; and a secondary component carrier may be an uplinksecondary component carrier, or may be a downlink secondary componentcarrier, but the embodiments of the present invention are not limitedthereto.

FIG. 1 is a schematic flowchart of a carrier switching method 100according to an embodiment of the present invention. The method may beperformed by a base station, and as shown in FIG. 1, the method 100includes:

S110: Determine, according to carrier switching capability informationof user equipment (UE), a carrier switching policy according to whichthe UE performs carrier switching.

S120: Send carrier switching indication information to the UE, where thecarrier switching indication information is used for indicating thecarrier switching policy, so that the UE performs carrier switchingaccording to the carrier switching policy.

Therefore, in the carrier switching method according to this embodimentof the present invention, UE having no carrier aggregation capability isenabled to dynamically perform switching between at least two carriers,so that quality of service of a service of the UE can be improved, userexperience can be improved, and system performance can be improved.

This embodiment of the present invention is applicable to UE having nocarrier aggregation capability, that is, the UE cannot receive and/orsend data on more than one carrier at a same moment. However, in thisembodiment of the present invention, the UE may have a carrier switchingcapability, that is, the UE may separately receive and/or send data ondifferent carriers at different moments. It should be understood that,in this embodiment of the present invention, that the UE has no carrieraggregation capability may refer to that the UE has no uplink carrieraggregation capability but has a downlink carrier aggregationcapability, or the UE has no downlink carrier aggregation capability buthas an uplink carrier aggregation capability, or refer to that the UEhas neither an uplink carrier aggregation capability nor a downlinkcarrier aggregation capability. Correspondingly, that the UE has acarrier switching capability may refer to that the UE has only an uplinkcarrier switching capability, or the UE has only a downlink carrierswitching capability, or refer to that the UE has both an uplink carrierswitching capability and a downlink carrier switching capability, butthis embodiment of the present invention is not limited thereto.However, even if the UE has the uplink carrier aggregation capability orthe downlink carrier aggregation capability, because the UE has nocarrier aggregation capability in the other direction, that is, thedownlink carrier aggregation capability or the uplink carrieraggregation capability, it is very difficult to apply the carrieraggregation capability of the UE in practice. For example, in anon-ideal backhaul situation, information between two carriers cannot betransmitted in real time, so that it is very difficult to apply aunidirectional carrier aggregation capability, but this embodiment ofthe present invention is not limited thereto.

In S110, the carrier switching capability information of the UE maydenote information about a specific capability that the UE supportscarrier switching. Optionally, the carrier switching capability of theUE may include a carrier baseband processing capability and/or a radiofrequency processing capability supported by the UE, andcorrespondingly, the carrier switching capability information of the UEmay include at least one piece of the following information: informationabout a quantity of carriers supported by the UE, information about acarrier frequency band supported by the UE and information about acarrier switching type supported by the UE. The information about aquantity of carriers supported by the UE may denote that the UE supportsmaintaining synchronization with N carriers simultaneously, and/or theUE supports performing radio resource management (RRM) measurement orchannel state information (CSI) measurement and feedback on N carriers,where N is an integer greater than or equal to 2. The information abouta carrier frequency band supported by the UE denotes a frequency band onwhich the UE separately supports uplink and/or downlink transmission, adownlink carrier frequency band supported by the UE may be differentfrom an uplink carrier frequency band supported by the UE, that is,uplink and downlink carrier frequency band capabilities supported by theUE may be different. The information about a carrier switching typesupported by the UE denotes switching between which carriers, of atleast three carriers, is supported by the UE when the UE supports the atleast three carriers, and the information may include switching betweenwhich uplink carriers is supported by the UE and/or switching betweenwhich downlink carriers is supported by the UE, but this embodiment ofthe present invention is not limited thereto.

A carrier switching mechanism of the UE having no carrier aggregationcapability may be UE-specific, and is activated by the base station byusing high-layer configuration signaling. Optionally, a new UEcapability may be defined. Carrier switching may affect a duplex spacingof reception and transmission of the UE, for example, switching isseparately performed on uplink and downlink carriers, and in this way,the UE may perform data and signaling transmission with the base stationon uplink and downlink carriers that are not system-associated;therefore, a new duplex spacing needs to introduced, which is one offactors for which a new UE capability may be introduced. Factors such asrequirements on measurement, a radio frequency structure, andsynchronization between multiple carriers may also need to be supportedby a new UE capability. Specifically, whether the UE supports a new UEcapability may be determined in a UE reporting manner, and if the UEsupports the new UE capability, the base station configures and uses thenew UE capability, but this embodiment of the present invention is notlimited thereto.

Optionally, the carrier switching capability information of the UE maybe pre-defined, or before determining the carrier switching policy ofthe UE, the base station obtains the carrier switching capabilityinformation of the UE, where optionally, the base station may obtain thecarrier switching capability information by receiving the carrierswitching capability information actively sent by the UE, or byreceiving the carrier switching capability information that is sent bythe UE according to an instruction that is sent by the base station andis used for instructing the UE to send the carrier switching capabilityinformation, but this embodiment of the present invention is not limitedthereto. Correspondingly, before S110, the method 100 further includes:

S130: Receive the carrier switching capability information of the UEthat is sent by the UE.

Optionally, as another embodiment, the base station may also select,according to the carrier switching capability information of the UE andchannel state information of carriers supported by the UE, at least twocarriers from the carriers supported by the UE to form a candidatecarrier set according to which the UE performs carrier switching, sothat the UE performs switching between the carriers in the candidatecarrier set. The channel state information of the foregoing carriers maybe obtained by measuring the carriers. Specifically, the base stationmay instruct the UE to measure a reference signal sent on downlinkcarriers, and determine channel state information of the downlinkcarriers according to a measurement result reported by the UE; and thebase station may also instruct the UE to send a reference signal on eachuplink carrier, and measure the reference signal on each uplink carrier,so as to determine channel state information of each uplink carrier, butthis embodiment of the present invention is not limited thereto.

Optionally, the base station may also determine the carrier switchingpolicy of the UE according to a switching time delay for carrierswitching pre-configured by a system, and may notify the UE of theswitching time delay for which the UE performs carrier switching, sothat the UE and the base station communicate on the basis ofconsistently understanding the switching time delay for carrierswitching, thereby avoiding that the base station needs to notify the UEof the switching time delay each time the base station instructs, byusing the switching indication information, the UE to perform carrierswitching. Correspondingly, before S110, the method 100 furtherincludes:

S140: Send first indication information to the UE, where the firstindication information is used for indicating a candidate carrier setaccording to which the UE performs carrier switching and/or a switchingtime delay for which the UE performs carrier switching.

The candidate carrier set may include a primary component carrier and atleast one secondary component carrier of the UE, where the primarycomponent carrier is semi-statically configured, and is mainly used forkeeping coverage and an RRC connection; the UE performs radio linkmonitoring and determining on the RRC connection according to theprimary component carrier; and the primary component carrier does notchange with carrier switching. Optionally, the primary component carriermay also change with carrier switching, that is, a current operatingcarrier of the UE is the primary component carrier, as the UE performscarrier switching, it means switching of the primary component carrier,and in this case, the UE always performs radio link monitoring anddetermining on the RRC connection according to the current operatingcarrier, but this embodiment of the present invention is not limitedthereto.

It should be understood that, in this embodiment of the presentinvention, the switching time delay for which the UE performs carrierswitching refers to a time actually consumed by the UE to performcarrier switching, and the switching time delay may include an inherenttime delay caused by a capability of the UE itself and an applicationscenario, and may further include a time delay offset configured by anetwork side for the UE. The inherent time delay of the UE may change asa carrier switching scenario changes. In a carrier switching situationin which a current carrier and a target carrier are consecutivecarriers, a typical value of the inherent time delay is one subframe. Ina carrier switching situation in which the current carrier and thetarget carrier are inter-band, the inherent time delay may differaccording to different capabilities of UEs. If UE can supportmaintaining synchronization with the inter-band current carrier andtarget carrier, the inherent time delay may be one subframe; for anotherUE that cannot maintain synchronization with the inter-band currentcarrier and target carrier, the inherent time delay may reach dozens ofsubframes, and a specific value thereof depends on a capability of theUE and specific implementation, but this embodiment of the presentinvention is not limited thereto.

Optionally, the switching time delay may be preset, and it can be knownfrom the foregoing description that, the switching time delay of the UEmay change as a scenario changes; therefore, for the switching timedelay preset by the system, factors such as a capability of the UE andsupporting on all scenarios need to be considered. Optionally, the basestation may also configure the switching time delay in advance by usinghigh-layer dedicated signaling or system broadcast signaling, and inthis case, the value of the switching time delay may be relativelyflexibly configured, but this embodiment of the present invention is notlimited thereto.

Optionally, the base station may also dynamically determine, accordingto a current network status, whether the UE needs to perform carrierswitching and determine a target carrier to which the carrier switchingis performed. Correspondingly, S110: Determine, according to carrierswitching capability information of UE, a carrier switching policyaccording to which the UE performs carrier switching includes:

S111: Determine, according to the carrier switching capabilityinformation of the UE and current network status information, thecarrier switching policy according to which the UE performs carrierswitching.

The current network status information may include: channel stateinformation of carriers supported by the UE or of carriers in acandidate carrier set that is configured by a base station for the UE,load information of carriers supported by the UE or of carriers in acandidate carrier set that is configured by a base station for the UE,and/or the like. In this way, the base station can better balance loadsof the carriers, and provide better quality of service for the UE, butthis embodiment of the present invention is not limited thereto.

Optionally, the carrier switching policy may include an uplink carrierswitching policy, that is, the UE switches from a current uplink carrierto a target uplink carrier, and keeps a downlink carrier unchanged.Optionally, the carrier switching policy may also include a downlinkcarrier switching policy, that is, the UE switches from a currentdownlink carrier to a target downlink carrier, and keeps an uplinkcarrier unchanged. Optionally, as another embodiment, the carrierswitching policy may also include an uplink carrier switching policy anda downlink carrier switching policy, where the uplink carrier switchingpolicy and the downlink carrier switching policy may be the same, thatis, the UE completes, in an M^(th) subframe after a current subframe,switching from a current uplink carrier to a target uplink carrier andswitching from a current downlink carrier to a target downlink carrier.Optionally, the current uplink carrier and the current downlink carriermay be a pair of system-associated carriers, and the target uplinkcarrier and the target downlink carrier may be a pair ofsystem-associated carriers. Optionally, the uplink carrier switchingpolicy may be different from the downlink carrier switching policy.Specifically, the uplink carrier switching may be completed in an M^(th)subframe after the current subframe, and the downlink carrier switchingmay be completed in an N^(th) subframe after the current subframe, whereboth N and M are integers greater than zero and N≠M, but the targetuplink carrier and the target downlink carrier are a pair ofsystem-associated carriers; or both the uplink carrier switching and thedownlink carrier switching are completed in an M^(th) subframe after thecurrent subframe, but the target uplink carrier and the target downlinkcarrier are not system-associated carriers; or the uplink carrierswitching and the downlink carrier switching are completed in an M^(th)subframe and an N^(th) subframe after the current subframe respectively,and the target uplink carrier and the target downlink carrier are notsystem-associated carriers, but this embodiment of the present inventionis not limited thereto.

Optionally, the uplink carrier switching policy and/or the downlinkcarrier switching policy in the carrier switching policy may includebeginning to perform switching in an L^(th) subframe after the currentsubframe and a switching time delay for the carrier switching, where Lis an integer greater than or equal to 0. The current subframe denotes asubframe in which the base station sends the carrier switchingindication information to the UE, in other words, denotes a subframe inwhich the UE receives the carrier switching indication information.Specifically, a value of L may be pre-defined by the system, forexample, a value of 0 denotes that once receiving the carrier switchingindication information in the current subframe, the UE starts carrierswitching, and in this case, the base station does not need to notify abeginning time of the carrier switching by using additional signaling,so as to save signaling overheads. Optionally, the base station may alsoflexibly determine the value of L according to factors such as a servicetransmission amount of the UE, a feedback time and a carrier thatcorrespond to a data channel, and in this way, the base station mayconfigure, by using specific signaling, the value of L corresponding tocarrier switching performed by the UE, but this embodiment of thepresent invention is not limited thereto.

Optionally, as another embodiment, when both the base station and the UEmay learn a switching time delay for carrier switching before thecarrier switching, for example, before performing carrier switching, theUE receives first indication information that is sent by the basestation and is used for indicating the switching time delay. The basestation may also indicate only a time at which the UE completes thecarrier switching, that is, indicate that the UE completes switching inan M^(th) subframe after the current subframe, and does not explicitlyindicate a beginning time of the carrier switching by using the carrierswitching indication information, but implicitly indicates, by using asubframe in which the carrier switching indication information is sent,a beginning time at which the UE performs the carrier switching, where avalue of M may depend on the switching time delay for the carrierswitching. Specifically, the base station and the UE may preset that theUE begins to perform switching in a current subframe in which thecarrier switching indication information is received, and after aswitching time delay of T subframes, the base station considers bydefault that the UE has already completed carrier switching, where T isan integer greater than zero, and in this case, M may be an integergreater than or equal to T. Optionally, the base station and the UE mayalso preset that the UE begins to perform switching after a subframeoffset when receiving the carrier switching indication information, forexample, begins to perform switching in an L^(th) subframe after thecurrent subframe, where L is an integer greater than zero, and in thiscase, M may be an integer greater than or equal to L+T. Optionally, asanother embodiment, when the carrier switching needs to be performedafter data transmission is performed with the base station, a value of Mmay also be related to a factor related to data transmission, forexample, the base station stipulates that a maximum quantity of times ofdata transmission is two, where M may be equal to a quantity ofsubframes that are needed to perform data transmission two times and tosend, by the UE, an acknowledgement (ACK) or negative-acknowledgement(NACK) feedback or receive an ACK/NACK feedback sent by the basestation, but this embodiment of the present invention is not limitedthereto.

Optionally, the carrier switching policy includes completing carrierswitching from a current downlink carrier to a target downlink carrierin an M1^(th) subframe after a current subframe in which the carrierswitching indication information is sent to the UE, where M1 is aninteger greater than or equal to 1.

Optionally, as another embodiment, the carrier switching policy includescompleting carrier switching from a current uplink carrier to a targetuplink carrier in an M2^(th) subframe after the current subframe inwhich the carrier switching indication information is sent to the UE,where M2 is an integer greater than or equal to 1.

For values of M1 and M2, reference may be made to the foregoingdescription for M, which is not described herein again for purpose ofconciseness. Moreover, in this embodiment of the present invention, thatthe UE completes carrier switching in a subframe denotes that the UE cancommunicate with the base station in the subframe by using a targetcarrier, but this embodiment of the present invention is not limitedthereto.

Optionally, as another embodiment, when the carrier switching policyincludes an uplink carrier switching policy and a downlink carrierswitching policy, and uplink and downlink carriers before and after thecarrier switching are a pair of system-associated carriers each, a timeconsumed by the UE to perform downlink carrier switching and a timeconsumed by the UE to perform uplink carrier switching may be differentbecause of different uplink and downlink carrier switching capabilitiesof the UE. In this case, the base station may configure a time delayoffset for the UE, so that a time actually consumed by the UE to performdownlink switching is equal to a time actually consumed by the UE toperform uplink switching; therefore, the UE operates on a pair ofsystem-associated carriers at a same moment, which does not affect datatransmission between the base station and the UE, and the UE may alwaysperform data transmission and HARQ feedback according to radio resourceconfigurations of the pair of system-associated carriers. Optionally,even if the uplink and downlink carrier switching capabilities of the UEare the same, the base station may also configure a time delay offsetfor the UE to separately trigger uplink and downlink carrier switching,so that data transmission of the UE and HARQ feedback corresponding tothe data transmission are maintained on a pair of system-associatedcarriers as much as possible, but this embodiment of the presentinvention is not limited thereto.

Correspondingly, when the current downlink carrier and the currentuplink carrier in the carrier switching policy are system-associatedcarriers, and the target downlink carrier and the target uplink carrierto which the UE performs carrier switching are system-associatedcarriers, a time needed to switch the UE from the current downlinkcarrier to the target downlink carrier is equal to a time needed toswitch the UE from the current uplink carrier to the target uplinkcarrier.

FIG. 2 is a schematic diagram in which a switching time consumed byuplink carrier switching is equal to that consumed by downlink carrierswitching in a carrier switching policy according to an embodiment ofthe present invention. As shown in FIG. 2, a base station sends DCI toUE in a subframe 1, where the DCI is used for scheduling PDSCHtransmission that is on a downlink carrier 1, and instructing the UE toswitch from the downlink carrier 1 to a downlink carrier 2. The UEdetects the DCI in the subframe 1, receives, according to the DCI, aPDSCH sent by the base station, and performs downlink carrier switchingafter receiving data. Assuming that a switching time consumed by theswitching is one subframe, the UE completes switching from the downlinkcarrier 1 to the downlink carrier 2 in a subframe 3, and continuouslymonitors the downlink carrier 2 until the base station triggers the UEagain to perform downlink carrier switching. In the subframe 3, the basestation schedules PUSCH transmission that is on an uplink carrier 2, andin this case, the base station triggers the UE to switch from an uplinkcarrier 1 to the uplink carrier 2. Because the UE needs to feed backACK/NACK to the base station on the uplink carrier 1 that issystem-associated with the downlink carrier 1, the UE uses the uplinkcarrier 1 in a subframe 5 to perform ACK/NACK feedback and then beginsto perform uplink carrier switching, and completes uplink carrierswitching in a subframe 7. In this way, a switching time consumed byuplink carrier switching of the UE is the same as that consumed bydownlink carrier switching of the UE, and the UE completes downlinkcarrier switching and uplink carrier switching in the subframe 3 and thesubframe 7 respectively; therefore, performing, by the base station,data scheduling on the UE is not affected, but this embodiment of thepresent invention is not limited thereto.

It is worth noting that, an uplink carrier switching process also needsa switching time delay. Optionally, the UE may start switching whenreceiving signaling used by the base station to schedule an uplinksignal, and it is ensured that at a moment when a signal needs to besent, switching is completed and the signal is sent. However, indifferent scenarios, switching time delays for which the UE performscarrier switching may be different. In a situation in which a currentuplink carrier and a target uplink carrier belong to a same timingadvance group (TAG), a switching time delay for which the UE performsuplink carrier switching is a processing time delay brought about in aprocess of synchronization between the UE and the base station on thetarget uplink carrier and may not be further considered, and because atiming advance of synchronization between the UE and the base station onthe current uplink carrier is equal to a timing advance ofsynchronization between the UE and the base station on the target uplinkcarrier, the UE may determine the timing advance of synchronizationbetween the UE and the base station on the target uplink carrieraccording to the timing advance of synchronization between the UE andthe base station on the current uplink carrier, and in this case, noadditional switching time delay is needed. However, in a situation inwhich the current uplink carrier and the target uplink carrier belong todifferent TAGs, a switching time delay of several subframes may beadditionally needed to complete a synchronization process, a specificvalue of the switching time delay depends on a time in which an uplinkperforms synchronization, such as, needs to be equal to dozens ofmilliseconds, and the value of the switching time delay may beconfigured. In this case, the base station may first trigger to send arandom access channel (RACH) to perform carrier switching, and in thisway, the switching time delay may not be specifically stipulated, but ifthe base station still uses another signal triggering manner, besides anexisting timing stipulated between a moment at which the UE receivesscheduling or configuration signaling of an uplink signal sent by thebase station and a moment at which the UE sends a signal, an additionalswitching time delay is further needed, but this embodiment of thepresent invention is not limited thereto.

Optionally, the base station may send downlink control information (DCI)carrying the carrier switching indication information, where the DCI maybe sent on a physical downlink control channel PDCCH) or an enhancedphysical downlink control channel (EPDCCH).

Optionally, the carrier switching indication information is carried indownlink control information DCI, where the DCI is further used forinstructing the UE to receive downlink data on the current downlinkcarrier; or

the carrier switching indication information is carried in DCI, wherethe DCI is further used for instructing the UE to send uplink data onthe current uplink carrier or on the target uplink carrier to whichcarrier switching is performed; or

the carrier switching indication information is carried in DCI, wherethe DCI is used for instructing the UE to perform carrier switchingaccording to the carrier switching policy and is not used for datascheduling.

The carrier switching indication information may be carried in downlinkcontrol information DCI, where the DCI may be further used forscheduling the UE to receive a physical downlink shared channel (PDSCH)on a current downlink carrier. Specifically, the DCI may be used forinstructing the UE to perform uplink and/or downlink carrier switching,and instructing the UE to receive data sent on the current downlinkcarrier. For example, the DCI is used for instructing the UE to receivedownlink data on the current downlink carrier, and to complete switchingfrom the current downlink carrier to the target downlink carrier in anM1^(th) subframe after the current subframe, and correspondingly, the UEmay receive, in the current subframe according to the DCI, the downlinkdata sent on the current downlink carrier, and perform carrier switchingafter receiving the downlink data. In this way, even if the DCI is usedfor instructing the UE to perform downlink carrier switching, it can bealso ensured that the existing timing may be used as a timing of the DCIand the PDSCH corresponding to the DCI, that is, downlink DCI and acorresponding PDSCH are transmitted in a same subframe, which does notbring about addition of additional hybrid automatic repeat request(HARD) design or increase of complexity of the UE because a new timingis introduced.

Optionally, as another embodiment, the carrier switching indicationinformation is carried in DCI, where the DCI may be further used forscheduling to send uplink data of a physical uplink shared channel(PUSCH) on the current uplink carrier or on the target uplink carrier towhich carrier switching is performed, and moreover the DCI is used forinstructing the UE to perform uplink and/or downlink carrier switching,and instructing the UE to send the uplink data to the base station,which may be specifically intra-carrier scheduling or inter-carrierscheduling, where the intra-carrier scheduling refers to scheduling datatransmission on an uplink carrier that is system-associated with thecurrent downlink carrier, and the inter-carrier scheduling refers toscheduling data transmission on an uplink carrier that is notsystem-associated with the current downlink carrier.

When the base station schedules data transmission on different uplinkcarriers in two consecutive subframes on a same downlink carrier, forexample, schedules data transmission of a current uplink carrier in acurrent subframe, and schedules data transmission of a target uplinkcarrier in a next subframe of the current subframe, because of aswitching time delay of the uplink carriers, the UE cannot perform datatransmission on different carriers separately in the two consecutivesubframes. In this case, one optional solution is: scheduling of thebase station is limited, that is, occurrence of this situation in thebase station is avoided; another optional solution is: an informationprocessing priority is set, for example, a priority of feedback ofaperiodic CSI is higher than that of sending of a PUSCH, or prioritiesare set for different uplink carriers, for example, data or a signal issent on a primary component carrier of the UE preferentially; andanother optional solution is: a switching time delay is set within arange of several symbols, and data transmission in a next subframe iscompressed within a symbol that is not affected, which may bespecifically a special PUSCH whose quantity of symbols is reduced, butthis embodiment of the present invention is not limited thereto.

Optionally, when the uplink carrier scheduled by the DCI is not thecurrent uplink carrier of the UE, a situation is: the DCI may alsoinstruct the UE to switch from the current uplink carrier to the targetuplink carrier, so that the UE completes transmission, on the targetuplink carrier, of uplink data scheduled by the DCI; and in anothersituation, for example, the DCI also instructs the UE not to performuplink carrier switching, and in this case, the UE may complete datatransmission only on an uplink carrier scheduled by the DCI, and thenstill operate on the current uplink carrier without performing carrierswitching. The UE may also consider that the indication of the DCI sentby the base station is erroneous, and the UE ignores the DCI andperforms no operation, but this embodiment of the present invention isnot limited thereto, where a specific behavior of the UE may bepre-defined, so that the base station and the UE have the sameunderstanding, thereby implementing unblocked communication, but thisembodiment of the present invention is not limited thereto.

Optionally, as another embodiment, the carrier switching indicationinformation is carried in DCI, where the DCI is used for instructing theUE to perform carrier switching according to the carrier switchingpolicy and is not used for data scheduling. In this case, other fieldsin the DCI may be jointly set to denote invalidity. For example, whenthe downlink of the UE uses a resource allocation type 0 and a resourceallocation type 1, if allocation resources of the DCI are all set to astate 0, it means that no resource is used to perform data transmission,which may indicate that this DCI is not used for data scheduling, butonly used for indicating carrier switching; or other manners in whichjoint field information is not specifically defined may be all used fordenoting that the DCI is not used for performing data scheduling, butthis embodiment of the present invention is not limited thereto.Optionally, the DCI may be transmitted in any format allowed by thecurrent subframe, but in consideration of a load saving factor, may betransmitted in a format of the shortest DCI, but this embodiment of thepresent invention is not limited thereto.

Optionally, when the DCI is further used for instructing the UE toreceive downlink data sent on the current downlink carrier, and thecarrier switching policy includes a downlink carrier switching policyand an uplink carrier switching policy, an offset value may existbetween beginning subframes of the uplink carrier switching and thedownlink carrier switching. Optionally, when the current uplink carrierand the current downlink carrier of the UE are a pair ofsystem-associated carriers, the offset value may be an integer greaterthan 4. In this way, the UE may receive the downlink data sent by thebase station on the current downlink carrier and perform carrierswitching to a downlink carrier in the current subframe, and feed backACK/NACK to the base station in a fourth subframe after the currentsubframe by using the current uplink carrier that is system-associatedwith the current downlink carrier. In this way, the UE may performfeedback by using existing HARQ timing, which does not bring aboutaddition of additional HARQ design and increase of complexity of the UEbecause a new timing is introduced.

Optionally, as another embodiment, the base station may indicate thecarrier switching policy in DCI in a manner of explicitly adding bits,where a quantity of the added bits may depend on a quantity of carrierssupported by the UE or a quantity of carriers in a candidate carrier setthat is configured by the base station for the UE, and/or depend on aquantity of times of performing carrier switching in the carrierswitching policy of the UE, such as, only performing downlink carrierswitching, or only performing uplink carrier switching, or performinguplink carrier switching and downlink carrier switching, but thisembodiment of the present invention is not limited thereto. Optionally,when the UE supports only two carriers or the candidate carrier setincludes only two carriers, only one bit may be added to the DCI, and“0” is used for indicating that carrier switching is not performed, “1”is used for indicating that carrier switching is performed, and theswitching is performed from the current carrier to the target carrier inthe candidate carrier set, or otherwise. Optionally, two bits may beadded to the DCI, where one bit is used for indicating whether toperform uplink carrier switching, and the other bit is used forindicating whether to perform downlink carrier switching, for example,when the two bits are both “1”, it denotes that the UE needs to performuplink carrier switching and downlink carrier switching, but thisembodiment of the present invention is not limited thereto.

Optionally, the DCI may multiplex three bits of a carrier indicatorfield (CIF) of inter-carrier scheduling in a carrier aggregationtechnology, the CIF is used for indicating a target carrier to whichcarrier switching is performed, and correspondingly, the carrierindicator field CIF included in the DCI is used for carrying the carrierswitching indication information. When the DCI is further used forinstructing the UE to receive downlink data on the current downlinkcarrier, the CIF is only used for indicating carrier switching, wherethe CIF corresponds to a target carrier index. Whether the UEspecifically performs uplink carrier switching and/or downlink carrierswitching needs to be determined according to a switching policy, ordetermined jointly with reference to another piece of indicationinformation. When the DCI is further used for instructing the UE to senduplink data on the current uplink carrier or on the target uplinkcarrier to which carrier switching is performed, the CIF may instructthe UE to only perform carrier switching, or may indicate both carrierswitching and a scheduled uplink carrier. Specifically, the network sidemay preset a carrier index and a CIF value corresponding to the carrierindex for each downlink carrier in the candidate carrier set of the UEand an uplink carrier that is system-associated with the downlinkcarrier, but this embodiment of the present invention is not limitedthereto.

Optionally, when the DCI sent by the base station on the currentdownlink carrier is used for scheduling data transmission on the currentuplink carrier, that is, current carrier scheduling, and an index valueof a CIF included in the DCI is not an index of the current carrier, theCIF may instruct the UE to only perform carrier switching, that is,instruct the UE to perform carrier switching from the current downlinkand/or uplink carrier to the target downlink and/or uplink carriercorresponding to a CIF index. Whether the UE specifically performsuplink carrier switching and/or downlink carrier switching needs to bedetermined according to the carrier switching policy, or determinedjointly with reference to another piece of indication information.Optionally, when the DCI sent by the base station on the currentdownlink carrier is used for scheduling data transmission on the targetuplink carrier, that is, inter-carrier scheduling, and a value of theCIF included in the DCI is an index of a target carrier, the CIFindicates both data scheduling and carrier switching on the targetuplink carrier corresponding to a CIF index, that is, instructs the UEto perform carrier switching from the current uplink carrier to thetarget uplink carrier. Whether the UE specifically further performsdownlink carrier switching needs to be determined according to aswitching policy, or determined jointly with reference to another pieceof indication information, but this embodiment of the present inventionis not limited thereto.

Optionally, as another embodiment, the base station may also indicatethe carrier switching policy in DCI in an implicit manner without addinga new bit to the DCI. Optionally, when the UE needs to switch from acurrent carrier to a target carrier, the base station may send the DCIto the UE on the current downlink carrier, and scramble the DCI by usinga cell identifier corresponding to the target carrier, so as to instructthe UE to switch from the current carrier to the target carrier, whichincludes: the UE may switch from a current downlink carrier to a targetdownlink carrier, and/or the UE may switch from a current uplink carrierto a target uplink carrier.

Specifically, the DCI may jointly instruct the UE to perform uplinkand/or downlink carrier switching while instructing the UE to performuplink or downlink data scheduling. For example, the base station maysend the DCI to the UE on the current downlink carrier, where the DCI isused for scheduling data transmission of the current downlink carrier orthe current uplink carrier, and scramble the DCI by using the cellidentifier corresponding to the target carrier, so as to instruct the UEto switch from the current carrier to the target carrier. Whether the UEspecifically performs uplink carrier switching and/or downlink carrierswitching needs to be determined according to a switching policy, ordetermined jointly with reference to another piece of indicationinformation. For example, when the DCI is used for scheduling downlinkdata transmission, the UE may be implicitly instructed to switch fromthe current downlink carrier to the target downlink carrier, while whenthe DCI is used for scheduling uplink data transmission, the UE may beimplicitly instructed to switch from the current uplink carrier to thetarget uplink carrier, but this embodiment of the present invention isnot limited thereto.

Optionally, the base station may also send the DCI to the UE on thecurrent downlink carrier, where the DCI is not used for data scheduling,and scramble the DCI by using the cell identifier corresponding to thetarget carrier, so as to instruct the UE to switch from the currentcarrier to the target carrier. Whether the UE specifically performsuplink carrier switching and/or downlink carrier switching needs to bedetermined according to a switching policy, or determined jointly withreference to another piece of indication information. For example, theDCI may be transmitted in an uplink format, a downlink format or anuplink and downlink unified format to further instruct the UE to performuplink carrier switching and/or downlink carrier switching, but thisembodiment of the present invention is not limited thereto.

Optionally, besides being indicated implicitly by scheduling uplink ordownlink data mentioned above, whether the DCI indicates uplink carrierswitching and/or downlink carrier switching may be further indicated byperforming scrambling by using two different cell identifiers of thetarget carrier, where one is a true cell identifier of the targetcarrier, and the other may be a virtual cell identifier of the targetcarrier. Specifically, when the DCI is scrambled by using the true cellidentifier of the target carrier, it indicates that the UE only performsuplink or downlink carrier switching, and whether it specificallyindicates uplink or downlink carrier switching may still be indicatedimplicitly by means of whether the DCI schedules uplink or downlinkdata; when the DCI is scrambled by using the virtual cell identifier ofthe target carrier, it indicates that the UE performs both uplinkcarrier switching and downlink carrier switching, but this embodiment ofthe present invention is not limited thereto.

Optionally, as another embodiment, the base station may also separatelypreconfigure, for carriers of the UE, one or more radio networktemporary identifiers (RNTI) corresponding to the carriers and acorrespondence between each identifier and carrier switching, where thecorrespondence is used for instructing the UE to perform uplink carrierswitching, downlink carrier switching, or perform both uplink carrierswitching and downlink carrier switching, and the DCI is scrambled byusing an RNTI corresponding to a target carrier, to implicitly instructthe UE to switch from a current carrier to the target carrier, but thisembodiment of the present invention is not limited thereto.

Optionally, as another embodiment, the base station may furtherimplicitly instruct the UE to switch from a current downlink carrier toa target downlink carrier by instructing, in DCI, the UE to feed backaperiodic channel state information CSI of the target downlink carrierto the base station. In this way, the UE not only may implementmeasurement on a channel state of the target downlink carrier, so as toobtain CSI feedback information of the target downlink carrier, but alsomay perform carrier switching, so as to reduce additional signalingbrought about because the base station instructs the UE to performcarrier switching, thereby saving signaling overheads, but thisembodiment of the present invention is not limited thereto.

Correspondingly, the DCI is scrambled by using a cell identifiercorresponding to a target carrier, so as to instruct the UE to switchfrom a current carrier to the target carrier; or the DCI instructs theUE to feed back channel state information of the target downlinkcarrier, so as to instruct the UE to switch from the current downlinkcarrier to the target downlink carrier.

It should be understood that, in this embodiment, a pair ofsystem-associated uplink and downlink carriers have a same cellidentifier. The current carrier and the target carrier may denote acurrent uplink carrier and a target uplink carrier respectively, andcorrespondingly, the DCI specifically instructs the UE to switch fromthe current uplink carrier to the target uplink carrier; or the currentcarrier and the target carrier denote a current downlink carrier and atarget downlink carrier respectively, and correspondingly, the DCI isspecifically used for instructing the UE to switch from the currentdownlink carrier to the target downlink carrier; or the current carrierand the target carrier denote a current uplink carrier and a currentdownlink carrier, and a target uplink carrier and a target downlinkcarrier respectively, in this case, the target uplink carrier and thetarget downlink carrier may be a pair of system-associated carriers, andcorrespondingly, the DCI specifically instructs the UE to switch fromthe current downlink carrier to the target downlink carrier, and switchfrom the current uplink carrier to the target uplink carrier that issystem-associated with the target downlink carrier, but this embodimentof the present invention is not limited thereto.

Optionally, as another embodiment, the base station may further instructthe UE to perform carrier switching in a manner of combining a carriersubframe pattern and the foregoing dynamic signaling (such as DCI), forexample, the network side may configure a carrier subframe pattern of aprimary component carrier for the UE in a pre-defined manner, or thebase station may preconfigure a carrier subframe pattern of a primarycomponent carrier of the UE for the UE by using high-layer signaling,where the carrier subframe pattern indicates subframes in which theprimary component carrier is reserved and used for receiving and/orsending data, and indicates, by using dynamic signaling in a subsequentcommunication process, a carrier that is used by the UE for receivingand/or sending data in other subframes. The primary-component-carriersubframe pattern configured by the base station has a priority higherthan that of the dynamic signaling, and the UE may perform measurement,synchronization, carrier resetting, maintenance of a connection betweenthe UE and the primary component carrier, system message updating andreceiving, and the like in reserved subframes of theprimary-component-carrier subframe pattern, but this embodiment of thepresent invention is not limited thereto.

In this embodiment, both the base station and the UE may learn that theother party performs data scheduling or transmission in the reservedsubframes of the primary-component-carrier subframe pattern. In thisway, both the UE and the base station may determine behaviors of theother party in these subframes, so as to avoid a problem of inconsistentunderstanding of the UE and the base station brought about because ofunreliable receiving of the dynamic signaling. For example, the basestation sends carrier switching indication information to instruct theUE to switch from a current downlink carrier to a target downlinkcarrier, but the UE has not received the carrier switching indicationinformation, and still monitors the current downlink carrier, and inthis case, because of inconsistent understanding of the UE and the basestation, problems such as potential packet loss and service interruptionmay be caused. Therefore, a manner of using a carrier subframe patternmay further improve system performance and user experience.

Correspondingly, before S110, the method 100 further includes:

S150: Determine a primary-component-carrier subframe pattern of the UE,where the primary-component-carrier subframe pattern is used forinstructing the UE to communicate with a base station in a firstsubframe by using a primary component carrier of the UE.

Correspondingly, S110: Determine, according to carrier switchingcapability information of UE, a carrier switching policy according towhich the UE performs carrier switching includes:

S112: Determine the carrier switching policy of the UE according to thecarrier switching capability information of the UE and theprimary-component-carrier subframe pattern.

Optionally, the network side may also configure a carrier subframepattern of at least one secondary component carrier for the UE in apre-defined manner or by using high-layer signaling, so as to indicatereserved subframes in which the UE receives and/or sends data by usingthe at least one secondary component carrier, and for another unreservedsubframe, the network side may further indicate, by using dynamicsignaling, a carrier that is used by the UE to receive and/or send datain the another subframe, but this embodiment of the present invention isnot limited thereto.

For design of a carrier subframe pattern of a primary component carrierand/or at least one secondary component carrier of the UE, factors suchas a quantity of candidate activated carriers of the UE, and measurementrequirements may be considered, and a reserved subframe may have arelatively long distribution period, so as to satisfy requirements thatthe UE performs measurement, synchronization, carrier resetting,maintenance of a connection between the UE and the primary componentcarrier, system message updating and receiving, and the like in reservedsubframes of the primary-component-carrier subframe pattern. On acarrier subframe pattern of each carrier, there may be several reservedsubframes in dozens of milliseconds. Optionally, subframes reserved fora primary component carrier and/or at least one secondary componentcarrier of the UE may be orthogonally distributed, and in this way, theUE may determine a carrier used by the UE in each reserved subframe,properly use network resources, and cause no confusion. Moreover, arequirement on a delay for which the UE performs switching betweencarriers may be further considered, for example, a subframe consumed bycarrier switching is not listed as a reserved subframe of any carrier,but this embodiment of the present invention is not limited thereto.

Optionally, because a primary component carrier of the UE needs to beused for maintaining an RRC connection, detecting a system message, andthe like, a carrier subframe pattern of the primary component carrier ofthe UE may be different from a carrier subframe pattern of a secondarycomponent carrier, such as, a location of a reserved subframe, aquantity of reserved subframes, and a period of a reserved subframe.Optionally, a reserved subframe of the primary component carrier mayhave a relatively short distribution period, such as 40 ms, and reservedsubframes of at least one secondary component carrier of the UE may bethe same and have longer distribution periods, such as 80 ms, and inthis case, there may be an offset between reserved subframes ofsecondary component carriers, or each secondary component carrier isseparately defined. Optionally, a location of a reserved subframe of acarrier subframe pattern of the primary component carrier may bedifferent from that of the secondary component carrier, but thisembodiment of the present invention is not limited thereto.

Optionally, when at least two carriers used by the UE to perform carrierswitching are carriers of an FDD system, the UE may still performfeedback by using a timing relationship of the FDD system, where datatransmission between the UE and the base station and ACK/NACK feedbackcorresponding to the data transmission may be performed on a pair ofsystem-associated carriers, or may not be performed on a pair ofsystem-associated carriers. If the data transmission and the ACK/NACKfeedback corresponding to the data transmission are not performed onsystem-associated carriers, resources needed by the ACK/NACK feedbackmay be reserved on each corresponding carrier, and the UE or the basestation may perform corresponding feedback according to carrierswitching and currently operating uplink and downlink carriers, but thisembodiment of the present invention is not limited thereto.

Optionally, each HARQ process and each transmission block of the UE maycorrespond to only one carrier, that is, initial transmission andretransmission of the transmission block are performed on only onecarrier. In this case, besides considering a time sequence relationshipbetween data transmission and ACK/NACK corresponding to the datatransmission, a time sequence relationship between initial transmissionof data and retransmission of the data needs to be further considered,and specifically, FDD downlink data transmission of LTE uses a timesequence relationship between initial transmission of data andretransmission of the data that are asynchronous; therefore, downlinkdata retransmission of the UE depends on scheduling of the base station,and is not strictly limited in a time sequence; and FDD uplink datatransmission of LTE may use an adaptive synchronization HARQtransmission mechanism, that is, downlink ACK/NACK feedback of uplinkdata may trigger the UE to perform uplink data retransmission at a fixedretransmission moment, and the base station does not need to perform newretransmission scheduling, the adaptive synchronization HARQtransmission mechanism fixes a time sequence relationship betweeninitial transmission of data and retransmission corresponding to thedata, but when both each HARQ process and each transmission block arelimited to correspond to one carrier, dynamic carrier switching of theUE or a carrier subframe pattern of a carrier of the UE needs toconsider a time sequence of an HARQ timing. In this way, for at leasttwo carriers of different base stations of non-ideal backhaul, each pairof system-associated carriers may be independently operated andscheduled without depending on data transmission between the basestation and the UE and ACK/NACK feedback corresponding to the datatransmission, but this embodiment of the present invention is notlimited thereto.

Optionally, as another embodiment, each HARQ process and eachtransmission block of the UE may correspond to at least two carriers,that is, initial transmission of the transmission block andretransmission thereof may be performed on the at least two carriers,but each transmission is performed on only one carrier. In this case,HARQ processes on the at least two carriers may be shared, and resourcesneeded for uplink and downlink ACK/NCK feedback need to be separatelyreserved on each carrier of the at least two carriers, and a datareceive end may perform corresponding feedback according to carrierswitching. In this way, for at least two carriers of different basestations of ideal backhaul, the at least two carriers may cooperate witheach other and be jointly scheduled, dynamic carrier switching or areserved subframe on a carrier subframe pattern may be configuredrelatively flexibly without being limited or constrained by an HARQtiming mechanism.

Optionally, the carrier switching method of this embodiment of thepresent invention may also be applied to a TDD system, and in this case,at least two TDD carriers correspond to different frequency spectrums,but this embodiment of the present invention is not limited thereto.When the at least two carriers used by the UE to perform carrierswitching are carriers of the TDD system, the UE may still performfeedback by using a timing relationship of the TDD system. Optionally,each HARQ process and each transmission block may correspond to only onecarrier, or may correspond to at least two TDD carriers, and a specificimplementation manner thereof is similar to that of the FDD system,which is not described herein again for purpose of conciseness.

Optionally, as another embodiment, the base station may furtherindicate, completely in a carrier subframe pattern manner, carrierswitching performed by the UE in a period of time, a value of the periodof time may be determined or pre-defined by the base station accordingto a current channel state and/or load stability of the at least twocarriers, a carrier subframe pattern of a carrier is used for denoting asubframe or subframes reserved and used for the carrier. For convenienceof description, a subframe reserved and used for the carrier is referredto as a reserved subframe of the carrier below, but this embodiment ofthe present invention is not limited thereto.

Correspondingly, the carrier switching policy includes carrier subframepatterns of at least two carriers, a carrier subframe pattern of eachcarrier of the at least two carriers is separately used for indicating areserved subframe in which the UE communicates with a base station byusing the carrier, and the carrier subframe patterns of the carriers arenot completely overlapped.

The base station may notify the UE of the carrier subframe patterns ofthe at least two carriers in a high-layer signaling manner. The at leasttwo carriers may be carriers in the candidate carrier set that isconfigured by the base station for the UE, and may include a primarycomponent carrier and at least one secondary component carrier, orinclude at least two secondary component carriers. Moreover, for designperformed by the base station on the carrier subframe patterns, factorssuch as a quantity of the carriers in the candidate carrier set of theUE, and a service transmission amount on each carrier need to beconsidered. Preferably, carrier subframe patterns of different carriersare completely orthogonal, that is, reserved subframes of differentcarriers are not overlapped with each other, and in this way, the UE maydetermine a carrier used by the UE in each subframe, properly usenetwork resources, and cause no confusion. Optionally, for design of thecarrier subframe patterns of the at least two carriers, a requirement ona delay for which the UE performs switching between carriers may befurther considered, that is, a subframe consumed by carrier switchingperformed by the UE is not listed as a reserved subframe of any carrier,but this embodiment of the present invention is not limited thereto.

Specifically, in the carrier subframe patterns of the at least twocarriers, reserved subframes of the carriers are orthogonal, and may beconfigured by means of staggered distribution, so that the UE monitorsonly one carrier in a same subframe. Optionally, the base station mayset different priorities for the at least two carriers, so that when thecarrier subframe patterns of the at least two carriers are overlappedafter being combined, the UE may preferentially monitor a carrier havinga higher priority, such as, the primary component carrier of the UE.Optionally, the carrier subframe patterns of the at least two carriersmay include all subframes in the period of time as much as possibleafter being combined, or include all other subframes in the period oftime after being combined except a subframe needed by a switching timedelay, so that the UE has a potentially available resource in eachsubframe. If there are still some subframes in which no carrier isreserved and used after the carrier subframe patterns of the at leasttwo carriers are combined, the system may use the primary componentcarrier by default, and in this way, the UE may monitor the primarycomponent carrier by default, but this embodiment of the presentinvention is not limited thereto.

Optionally, as another embodiment, the reserved subframes of the atleast two carriers may be periodically distributed, and have differentdistribution periods; or the reserved subframes of the at least twocarriers have a same distribution period, but there is an offset valuebetween initial locations of the reserved subframes. Optionally, acarrier subframe pattern of the primary component carrier of the UE maybe different from a carrier subframe pattern of another carrier, suchas, a location of a reserved subframe, a quantity of reserved subframes,and a period of a reserved subframe, but this embodiment of the presentinvention is not limited thereto.

Optionally, in a case of at least two candidate FDD carrier sets forwhich the UE performs carrier switching, the UE may still performfeedback by using the timing relationship of the FDD system. As shown inFIG. 3, the distribution periods of the reserved subframes of the atleast two carriers are 10 ms. Reserved subframes of the downlink carrier1 are subframes 0, 1, 4, 5, 8 and 9, and after the UE receives downlinkdata in the foregoing subframes, subframes in which the UE performsACK/NACK feedback are reserved, that is, reserved subframes of theuplink carrier 1 that is system-associated with the downlink carrier 1are subframes 4, 5, 8, 9, 2 and 3; and reserved subframes of thedownlink carrier 2 are subframes 2, 3, 6 and 7, and correspondingly,reserved subframes of the uplink carrier 2 that is system-associatedwith the downlink carrier 2 are subframes 6, 7, 0 and 1. It can be seenthat, carrier subframe patterns of the downlink carrier 1 and thedownlink carrier 2 are orthogonally distributed. Optionally, each HARQprocess and each transmission block may correspond to only one carrier,that is, both initial transmission and retransmission of thetransmission block are performed on a same carrier. In this case, forFDD uplink transmission of LTE, a carrier subframe pattern of theprimary component carrier or carrier subframe patterns of all carriersof the UE may use a common multiple of a quantity (such as 10) ofsubframes included in a radio frame and an HARQ timing time sequence(such as 8) as a distribution period of a reserved subframe, a specificcarrier subframe pattern thereof may be configured according to an HARQtiming time sequence relationship, and preferably, a minimum commonmultiple (such as 40) of the quantity of the subframes included in theradio frame and the HARQ timing time sequence may be selected as adistribution period of a reserved subframe, so as to save signalingoverheads. In this way, for at least two carriers of different basestations of non-ideal backhaul, each pair of system-associated carriersmay be independently operated and scheduled without depending on datatransmission between the base stations and ACK/NACK feedback of the datatransmission, but this embodiment of the present invention is notlimited thereto.

Optionally, as another embodiment, each HARQ process and eachtransmission block may correspond to at least two carriers, that is,initial transmission and retransmission of the transmission block may beperformed on the at least two carriers, but each transmission isperformed on only one carrier, and for specific configuration thereof,reference may be made to the foregoing corresponding embodiment in whicha carrier subframe pattern and dynamic signaling are combined and used,which is not described herein again for purpose of conciseness.

Optionally, a first subframe ratio in the at least two carriers is areciprocal of a second subframe ratio, the first subframe ratio is aratio between a quantity of reserved subframes of a first uplink carrierand a quantity of reserved subframes of a first downlink carrier, wherethe first uplink carrier and the first downlink carrier of the at leasttwo carriers are system-associated, and a relative relationship betweena location of a reserved subframe of the first uplink carrier and alocation of a reserved subframe of the first downlink carrier satisfiesa preset first TDD ratio configuration, where the second subframe ratiois a ratio between a quantity of reserved subframes of a second uplinkcarrier and a quantity of reserved subframes of a second downlinkcarrier, where the second uplink carrier and the second downlink carrierof the at least two carriers are system-associated; or

a ratio between subframes of a carrier subframe pattern of a thirddownlink carrier and subframes of a carrier subframe pattern of a fourthdownlink carrier of the at least two carriers is a first TDDconfiguration of seven preset time division multiplexing TDDconfigurations, where the carrier subframe pattern of the third downlinkcarrier corresponds to downlink and special subframes of the first TDDconfiguration, and the carrier subframe pattern of the fourth downlinkcarrier corresponds to an uplink subframe of the first TDDconfiguration.

When the at least two carriers used by the UE to perform carrierswitching are carriers of the FDD system, the UE may also performfeedback and transmit a periodic signal in a manner similar to that inthe TDD system, such as, a manner of using an HARQ timing time sequenceof TDD. For convenience of understanding, a ratio between a quantity ofreserved uplink subframes of an uplink carrier and a quantity ofreserved downlink subframes of a downlink carrier in a same period oftime is referred to as a quasi-TDD ratio between uplink subframes anddownlink subframes below, where the uplink carrier and the downlinkcarrier are a pair of system-associated carriers. For example, in the atleast two carrier subframe patterns, quasi-TDD ratios between uplinksubframes and downlink subframes of two pairs of system-associateduplink and downlink carriers may be reciprocals of each other, and areconfigurations of ratios between uplink subframes and downlink subframesof the existing TDD system. As shown in FIG. 4, a quasi-TDD ratiobetween uplink subframes and downlink subframes used by the uplinkcarrier 1 and the downlink carrier 1 that are system-associated is 2:3,and corresponds to a configuration 0 of the existing TDD system, and aquasi-TDD ratio between uplink subframes and downlink subframes used bythe uplink carrier 2 and the downlink carrier 2 that aresystem-associated is 3:2, and corresponds to a configuration 1 of theexisting TDD system. In this way, the UE may still perform feedback oneach carrier pair by using the existing HARQ timing relationshipcorresponding to the TDD ratio between uplink subframes and downlinksubframes without introducing a new HARQ timing time sequence andfeedback mechanism, and reuse a relatively common ratio configurationthat embodies uplink and downlink services in the existing TDD system,thereby optimizing system configuration. In particular, in a case of atleast two carriers of different base stations of non-ideal backhaul,each pair of system-associated carriers may be independently operatedand scheduled according to a respective configuration of the carrierpair without depending on data transmission between the base stationsand ACK/NACK feedback of the data transmission.

Optionally, when the at least two carriers used by the UE to performcarrier switching are carriers of the FDD system, and the at least twocarriers use carrier subframe patterns similar to that of the TDD uplinkand downlink configuration, if the existing HARQ timing time sequence ofTDD is reused, a sequence and serial numbers for subframes of the UE maykeep consistent with those of the TDD system. For example, as shown inFIG. 4, a UE-specific subframe sequence relationship may be introducedfor the UE that performs carrier switching, to correspond to locationsof uplink and downlink subframes in a radio frame and serial numbers ofthe subframes in the existing TDD uplink and downlink subframeconfiguration. However, because the at least two carriers themselves arecarriers of the FDD system, and particularly for the primary componentcarrier, because user equipment that communicates by using only thecarrier still exists, it needs to be considered that subframes used tosatisfy requirements such as synchronization and reception of a systemmessage and a paging message are reserved to keep consistent with theexisting FDD system, so as to keep compatibility of the carrier, so thatthe UE may keep an RRC connection and normal communication on theprimary component carrier of the UE, but in the existing FDD system, itis stipulated that a paging message can be transmitted in only subframesin each radio frame whose subframe numbers are 0, 4, 5 and 9, and otheroperations such as the synchronization and the reception of the systemmessage may also be performed in these subframes. In this way, from theviewpoint of the network side, for a sequence of subframe numbers ofsubframes, reference may be made to digits in each subframe block inFIG. 4; therefore, the UE performing carrier switching needs to maintainan additional group of UE-specific subframe numbers to be used formaintaining the HARQ mechanism, and also to maintain a group ofcell-specific subframe numbers to perform synchronization with the basestation, and receive a system message and a paging message, but thisembodiment of the present invention is not limited thereto.

Optionally, an offset value may exist between the UE-specific subframenumber and the cell-specific subframe number, FIG. 4 is used as anexample, for a carrier 1, a UE-specific subframe number is an offset tothe left by one subframe relative to a cell-specific subframe number, aspecific offset may depend on a TDD ratio between uplink subframes anddownlink subframes used by this carrier and the cell-specific subframenumber needs to be reserved; further, a TDD ratio between uplinksubframes and downlink subframes on a carrier 2 further needs to be alsoconsidered, an offset value also needs to exist between a UE-specificsubframe number corresponding to the carrier 2 and the UE-specificsubframe number corresponding to the carrier 1, this offset value ismainly to ensure that a sequence relationship of subframe numbers foreach carrier corresponds to the existing TDD uplink and downlinksubframe configuration used by the carrier, and specific locations ofuplink and downlink subframes in a radio frame and serial numbers of thesubframes in the TDD uplink and downlink subframe configuration, and fora sequence of UE-specific subframe numbers on the carrier 2, referencemay be made to digits above a subframe block of the carrier 2 in FIG. 4.

Additionally, it needs to be emphasized that, a cell-specific subframethat needs to be reserved on each FDD carrier may also be consideredaccording to use of the FDD carrier itself. For a primary componentcarrier, it needs to be considered that subframes for performingsynchronization and reception of a system message and a paging messageare reserved, so that the UE may keep an RRC connection and normalcommunication on the primary component carrier of the UE; and for asecondary component carrier on which the UE performs carrier switching,which subframes are reserved needs to be considered according to a typeand a configuration of the secondary component carrier, so that the UEmay normally communicate on the secondary component carrier.Specifically, one carrier type is a backward compatible carrier, eachsubframe transmits a cell-specific reference signal, and the UE maytrack time frequency synchronization and/or perform RRM measurementaccording to the cell-specific reference signal. Another carrier type isa new carrier type, this type of carrier only sends a cell-specificreference signal in a period in some and pre-defined subframes, and inthis way, the UE needs to monitor this carrier in these subframes totrack time frequency synchronization with this carrier and/or performRRM measurement, but this embodiment of the present invention is notlimited thereto.

Optionally, a carrier type relationship between the primary componentcarrier and the secondary component carrier may include two situations,where one situation is: the secondary component carrier and the primarycomponent carrier are of a same carrier type, and both are backwardcompatible carriers. In this case, each subframe of a backwardcompatible carrier transmits a cell-specific reference signal;therefore, no specific requirement is imposed on a subframe reserved onthe secondary component carrier. The other situation is: either theprimary component carrier or the secondary component carrier is of a newcarrier type, and in this case, it is considered that a subframe isreserved on either of the two carriers. Specifically, in a situation inwhich the primary component carrier is of the new carrier type,transmission of the cell-specific reference signal needs to be limitedin a paging subframe, and additional limitation needs to be consideredfor a subframe reserved on the primary component carrier; and in asituation in which the secondary component carrier is of the new carriertype, reservation of a subframe on the secondary component carrier needsto consider to include a subframe in which the cell-specific referencesignal is transmitted. For example, the cell-specific reference signalis transmitted in subframes whose subframe numbers mod 5 are 0, thesesubframes need to be reserved to be used by the secondary componentcarrier; and moreover, staggered configuration of the secondarycomponent carrier and the primary component carrier needs to beconsidered, and an offset value may also exist between cell-specificsubframe numbers of the primary and secondary component carriers. Forexample, as shown in FIG. 4, the cell-specific subframe number of thesecondary component carrier is an offset to the right by two subframesrelative to the cell-specific subframe number of the primary componentcarrier, and for a specific cell-specific subframe number, reference maybe made to a digit in each subframe block in the carrier 2. Further, theprimary component carrier and the secondary component carrier may have asame duplex standard, such as, be a same FDD or TDD system; or theprimary component carrier and the secondary component carrier havedifferent duplex standards, but this embodiment of the present inventionis not limited thereto.

Optionally, when quasi-TDD ratios between uplink subframes and downlinksubframes of two pairs of system-associated uplink and downlink carriersare reciprocals of each other, a combination of carrier subframepatterns of the two carriers may enable the UE to communicate with thebase station with potential available uplink and downlink resources ineach subframe. Additionally, other periodic CSI and SRS feedback may bealso performed with reference to the timing relationship of the existingTDD system, but this embodiment of the present invention is not limitedthereto.

Optionally, as another embodiment, in the carrier subframe patterns ofthe at least two carriers, quasi-TDD ratios between uplink subframes anddownlink subframes of two pairs of system-associated uplink and downlinkcarriers may be reciprocals of each other, but the TDD ratios betweenuplink subframes and downlink subframes may not completely correspond toratios between uplink subframes and downlink subframes of the existingTDD system. For example, a quasi-TDD ratio between uplink subframes anddownlink subframes used by a pair of system-associated uplink carrierand downlink carrier is 4:1, and corresponds to a ratio between uplinksubframes and downlink subframes 4:1 of the existing TDD system, thatis, a configuration 2 in Table 1, and a quasi-TDD ratio between uplinksubframes and downlink subframes used by another pair ofsystem-associated uplink carrier and downlink carrier is 1:4, but doesnot correspond to any ratio between uplink subframes and downlinksubframes of seven ratios between uplink subframes and downlinksubframes shown in Table 1 of the existing TDD system. In this case, asystem-associated carrier corresponding to a ratio between uplinksubframes and downlink subframes of the existing TDD system may bepreferentially defined as a primary component carrier of the UE, the UEmay perform feedback on the primary component carrier by using theexisting HARQ timing relationship corresponding to the TDD ratio, andperiodic CSI and SRS feedback performed on the primary component carriermay be also performed with reference to the timing relationship, of theexisting TDD system, corresponding to the TDD ratio. Moreover, anotherpair of system-associated carriers described above may be defined assecondary component carriers of the UE, a newly defined time sequencerelationship may be used as the HARQ timing thereof, or some feedback isperformed on the primary component carrier, and a time sequencerelationship between the pair of system-associated carriers is notlimited in this embodiment of the present invention. In this way,service transmission of the primary component carrier, and networkconnection and an HARQ mechanism of the service transmission in aneffective multiplexing TDD system can be effectively ensured, andparticularly, in a case of at least two carriers of different basestations of non-ideal backhaul, each pair of system-associated carriersmay be independently operated and scheduled according to a respectiveconfiguration of the carrier pair, and transmission of the primarycomponent carrier can be ensured without depending on intercommunicationdata between the base stations and ACK/NACK feedback of theintercommunication data.

Optionally, in another embodiment, when the at least two carriers usedby the UE to perform carrier switching are carriers of the FDD system,carrier subframe patterns of the at least two carriers may further use aformat of a quasi-TDD subframe ratio to denote reserved subframes of theat least two carriers, for example, as shown in Table 1, the candidatecarrier set that is configured by the base station for the UE includestwo carriers, where one may be defined as a primary component carrier,and the other may be defined as a secondary component carrier, and theUE may perform carrier switching between the primary component carrierand the secondary component carrier.

TABLE 1 A carrier subframe pattern uses a format of a quasi-TDD ratioCarrier subframe pattern Period Subframe number configuration (ms) 0 1 23 4 5 6 7 8 9 0 5 P P S S S P P S S S 1 5 P P S S P P P S S P 2 5 P P SP P P P S P P 3 10 P P S S S P P P P P 4 10 P P S S P P P P P P 5 10 P PS P P P P P P P 6 5 P P S S S P P S S P

P denotes a primary component carrier, S denotes a secondary componentcarrier, P corresponds to a downlink subframe and a special subframe ina TDD system, and S corresponds to an uplink subframe in the TDD system;in this case, the special subframe in the TDD system may be consideredas a normal downlink subframe, and a channel transmission mechanism isconfigured and controlled by using a reference signal of the normaldownlink subframe. There are totally seven carrier subframe patternconfigurations 0 to 6 in Table 1, and Table 1 separately shows carriertypes of the seven carrier subframe pattern configurations that arereserved in all subframes in a radio frame. For example, for the carriersubframe pattern configuration 0, a repetition period of a carriersubframe pattern is 5 ms, the UE reserves and uses a primary componentcarrier in subframes 0 and 1, and reserves and uses a secondarycomponent carrier in subframes 2, 3 and 4, and patterns of previous fivesubframes are repeated in subframes 5 to 9; and for the carrier subframepattern configuration 3, a repetition period of a carrier subframepattern is 10 ms, and the UE reserves and uses a secondary componentcarrier in subframes 2, 3 and 4, and reserves and uses a primarycomponent carrier in the rest subframes. The carrier subframe patternconfiguration shown in Table 1 may be only applied to a subframe patternconfiguration of a downlink carrier or an uplink carrier, that is, P andS denote a primary uplink carrier and a secondary uplink carrierrespectively, or denote a primary downlink carrier and a secondarydownlink carrier respectively, a subframe pattern configuration of acarrier in another direction corresponding to the carrier subframepattern configuration may depend on other configuration information ofthe base station; or the manner may be applied to subframe patternconfigurations of both an uplink carrier and a downlink carrier, andsubframe numbers in the subframe pattern configurations of the uplinkand downlink carriers may be in a one-to-one correspondence, but thisembodiment of the present invention is not limited thereto.

Optionally, when carrier subframe patterns of two candidate FDD carrierson which the UE performs carrier switching use a format of a quasi-TDDsubframe ratio, and the format of the quasi-TDD subframe ratio is onlyapplied to a downlink carrier, an uplink carrier on which the UEoperates may be any one of two candidate FDD uplink carriers used by theUE to perform carrier switching, and may preferably be an uplink primarycomponent carrier. In this way, both uplink feedback for uplink datatransmission and uplink feedback for downlink data transmission may becompleted on this uplink carrier, and the HARQ timing relationship ofthe FDD system may be still used. Particularly, in a case of at leasttwo carriers of different base stations of ideal backhaul, two carriersmay cooperate with each other and be jointly scheduled; therefore, theHARQ timing mechanism and feedback for downlink data may be flexiblyconfigured.

Similarly, when the carrier subframe pattern of the quasi-TDD subframeratio is applied to an uplink carrier, a downlink carrier on which theUE operates may be any one of two candidate FDD downlink carrier setsused by the UE to perform carrier switching, and may preferably be adownlink primary component carrier. In this way, uplink transmissionload may be balanced, and particularly, for a heterogeneous macro/microdeployment network, the UE sends uplink data and a control channel to asmall-cell base station in some subframes. Particularly, when the UE isrelatively close to the small-cell base station, transmit power of theUE may be saved, thereby reducing power consumption of the UE.

Optionally, the format of the quasi-TDD subframe ratio used by thecarrier subframe pattern may be also applied to carrier subframe patternconfigurations of both an uplink carrier and a downlink carrier, andsubframe numbers in the subframe pattern configurations of the uplinkand downlink carriers may be in a one-to-one correspondence. Forexample, in the carrier subframe pattern configuration 0, an uplinkprimary component carrier and a downlink primary component carrier thatis system-associated with the uplink primary component carrier arereserved and used in the subframe 0 and the subframe 1, and an uplinksecondary component carrier and a downlink secondary component carrierthat is system-associated with the uplink secondary component carrierare reserved and used in the subframes 2, 3 and 4. Optionally, there maybe an offset value between subframe numbers in subframe patternconfigurations of the uplink and downlink carriers, for example, in thecarrier subframe pattern configuration 0, an uplink primary componentcarrier is reserved and used in the subframe 0 and the subframe 1, and adownlink primary component carrier that is system-associated with theuplink primary component carrier is reserved and used and in thesubframe 4 and the subframe 5, there is an offset of four subframesbetween reserved subframes of the uplink primary component carrier andthe downlink primary component carrier, but this embodiment of thepresent invention is not limited thereto.

Optionally, in a method for indicating carrier switching by usingdynamic DCI signaling, or in a method for indicating carrier switchingof the UE in a period of time completely in a carrier subframe patternmanner, or for instructing the UE to perform carrier switching in amanner of combining a carrier subframe pattern and dynamic signaling,for configuration and transmission of uplink periodic signals CSI andSRS, available subframes of each uplink carrier need to be considered,and for a method for configuring a carrier subframe pattern, an optionalmanner is to use a fixed period, such as 10 ms, so that eachtransmission of the uplink signal definitely occurs on a fixed carrier.Moreover, for the method for dynamically indicating available subframesof each carrier or the method for combining a carrier subframe patternand dynamic signaling, one manner is to flexibly configure the feedbackperiod, such as 5 ms. In this case, when a transmission moment arrivesand a current subframe is not an available subframe of a currentcarrier, the UE may discard transmission of a current periodic signal,or determine whether to transmit the periodic signal according towhether another signal or data is transmitted on a carrier correspondingto the current subframe at a current moment, and if another signal ordata is transmitted on the carrier corresponding to the current subframeat the current moment, the UE may still send the another signal or dataon the carrier corresponding to the current subframe, and also discardsending of the periodic signal; or if another signal or data is nottransmitted on the carrier corresponding to the current subframe at thecurrent moment, the UE sends the periodic signal on the carriercorresponding to the current subframe, but this embodiment of thepresent invention is not limited thereto.

Therefore, in the carrier switching method according to this embodimentof the present invention, UE having no carrier aggregation capability isenabled to dynamically perform switching between at least two carriers,so that quality of service of a service of the UE can be improved,system load can be balanced, user experience can be improved and systemperformance can be improved.

The carrier switching method according to this embodiment of the presentinvention is described in detail from the viewpoint of a base stationwith reference to FIG. 1 and FIG. 4 above, and a carrier switchingmethod according to an embodiment of the present invention is describedin detail from the viewpoint of UE with reference to FIG. 5 below.

FIG. 5 is a schematic flowchart of a carrier switching method 200according to another embodiment of the present invention. As shown inFIG. 5, the method 200 includes:

S210: Receive carrier switching indication information sent by a basestation, where the carrier switching indication information is used forindicating a carrier switching policy according to which user equipmentUE performs carrier switching.

S220: Perform carrier switching according to the carrier switchingpolicy indicated in the carrier switching indication information.

Therefore, in the carrier switching method according to this embodimentof the present invention, UE having no carrier capability is enabled todynamically perform switching between at least two carriers, so thatquality of service of a service of the UE can be improved, userexperience can be improved, and system performance can be improved.

Optionally, the carrier switching policy may include an uplink carrierswitching policy and/or a downlink carrier switching policy.Correspondingly, the carrier switching policy includes completingcarrier switching from a current downlink carrier to a target downlinkcarrier in an M1^(th) subframe after a current subframe in which thecarrier switching indication information sent by the base station isreceived, where M1 is an integer greater than or equal to 1.

Optionally, as another embodiment, the carrier switching policy includescompleting carrier switching from a current uplink carrier to a targetuplink carrier in an M2^(th) subframe after the current subframe inwhich the carrier switching indication information sent by the basestation is received, where M2 is an integer greater than or equal to 1.

In this case, the UE may complete, according to the carrier switchingpolicy, switching in an M1^(th) subframe after the current subframe andcommunicate with the base station in the subframe.

Optionally, as another embodiment, when the current downlink carrier andthe current uplink carrier in the carrier switching policy aresystem-associated carriers, and the target downlink carrier and thetarget uplink carrier to which the UE performs carrier switching aresystem-associated carriers, a time needed to switch the UE from thecurrent downlink carrier to the target downlink carrier is equal to atime needed to switch the UE from the current uplink carrier to thetarget uplink carrier.

Optionally, as another embodiment, the carrier switching indicationinformation is carried in downlink control information DCI, where theDCI is further used for instructing the UE to receive downlink data onthe current downlink carrier; or

the carrier switching indication information is carried in DCI, wherethe DCI is further used for instructing the UE to send uplink data onthe current uplink carrier or on the target uplink carrier to whichcarrier switching is performed; or

the carrier switching indication information is carried in DCI, wherethe DCI is used for instructing the UE to perform carrier switchingaccording to the carrier switching policy and is not used for datascheduling.

Optionally, as another embodiment, a carrier indicator field CIFincluded in the DCI is used for carrying the carrier switchingindication information.

The CIF may be only used for instructing the UE to perform carrierswitching, or may be both used for scheduling data transmission on thetarget uplink carrier, and used for instructing the UE to switch fromthe current uplink carrier to the target uplink carrier, but thisembodiment of the present invention is not limited thereto.

Optionally, as another embodiment, the DCI is scrambled by using a cellidentifier corresponding to a target carrier, so as to instruct the UEto switch from a current carrier to the target carrier; or

the DCI instructs the UE to feed back channel state information of thetarget downlink carrier, so as to instruct the UE to switch from thecurrent downlink carrier to the target downlink carrier.

A pair of system-associated uplink carrier and downlink carrier maycorrespond to a same cell identifier, and in this way, the UE maydetermine according to scrambling code information of the DCI to switchfrom the current uplink carrier to the target uplink carrier and/orswitch from the current downlink carrier to the target downlink carrier,where the target uplink carrier and the target downlink carrier aresystem-associated carriers, and specifically, performing uplink carrierswitching, performing downlink carrier switching or performing uplinkand downlink carrier switching may be further determined according toother information, but this embodiment of the present invention is notlimited thereto.

Optionally, as another embodiment, before S210, the method 200 furtherincludes:

S230: Determine a primary-component-carrier subframe pattern of the UE,where the primary-component-carrier subframe pattern is used forinstructing the UE to communicate with the base station in a firstsubframe by using a primary component carrier of the UE.

Correspondingly, S220: Perform carrier switching according to thecarrier switching policy indicated in the carrier switching indicationinformation includes:

S221: Perform carrier switching according to the carrier switchingpolicy and the primary-component-carrier subframe pattern.

The primary-component-carrier subframe pattern may include a carriersubframe pattern of a primary uplink carrier and/or a carrier subframepattern of a primary downlink carrier, the UE may preferably communicatewith the base station by using the primary component carrier in asubframe reserved for the primary component carrier in theprimary-component-carrier subframe pattern, and in this case, when theUE operates on a secondary component carrier, the UE may perform carrierswitching, so as to switch to the primary component carrier, therebyensuring that a carrier operating in the first subframe is the primarycomponent carrier, but this embodiment of the present invention is notlimited thereto.

Optionally, as another embodiment, the carrier switching policy includescarrier subframe patterns of at least two carriers, a carrier subframepattern of each carrier of the at least two carriers is separately usedfor indicating a reserved subframe in which the UE communicates with abase station by using the carrier, and the carrier subframe patterns ofthe carriers are not completely overlapped.

Optionally, as another embodiment, a first subframe ratio in the atleast two carriers is a reciprocal of a second subframe ratio, the firstsubframe ratio is a ratio between a quantity of reserved subframes of afirst uplink carrier and a quantity of reserved subframes of a firstdownlink carrier, where the first uplink carrier and the first downlinkcarrier of the at least two carriers are system-associated, and arelative relationship between a location of a reserved subframe of thefirst uplink carrier and a location of a reserved subframe of the firstdownlink carrier satisfies a preset first TDD ratio configuration, wherethe second subframe ratio is a ratio between a quantity of reservedsubframes of a second uplink carrier and a quantity of reservedsubframes of a second downlink carrier, where the second uplink carrierand the second downlink carrier of the at least two carriers aresystem-associated; or

a ratio between subframes of a carrier subframe pattern of a thirddownlink carrier and subframes of a carrier subframe pattern of a fourthdownlink carrier of the at least two carriers is a first TDDconfiguration of seven preset time division duplex (TDD) configurations,where the carrier subframe pattern of the third downlink carriercorresponds to downlink and special subframes of the first TDDconfiguration, and the carrier subframe pattern of the fourth downlinkcarrier corresponds to an uplink subframe of the first TDDconfiguration.

Optionally, as another embodiment, before S210, the method 200 furtherincludes:

S240: Send carrier switching capability information of the UE to thebase station, so that the base station determines the carrier switchingpolicy according to the carrier switching capability information.

Optionally, as another embodiment, the carrier switching capabilityinformation of the UE includes at least one piece of the followinginformation: information about a quantity of carriers supported by theUE, information about a carrier frequency band supported by the UE andinformation about a carrier switching type supported by the UE.

Optionally, as another embodiment, before S210, the method 200 furtherincludes:

S250: Receive first indication information sent by the base station,where the first indication information is used for indicating acandidate carrier set according to which the UE performs carrierswitching and/or a switching time delay for which the UE performscarrier switching.

Therefore, in the carrier switching method according to this embodimentof the present invention, UE having no carrier capability is enabled todynamically perform switching between at least two carriers, so thatquality of service of a service of the UE can be improved, system loadcan be balanced, user experience can be improved and system performancecan be improved.

It should be understood that the sequence numbers in the foregoingprocedures do not mean an execution sequence; the execution sequence ofthe procedures should be determined according to functions and internallogic thereof, and should not constitute any limitation to theimplementation process of the embodiment of the present invention.

The carrier switching methods according to the embodiments of thepresent invention are described in detail with reference to FIG. 1 toFIG. 5 above, and a base station, and user equipment according toembodiments of the present invention are described with reference toFIG. 6 to FIG. 9 below.

FIG. 6 is a schematic block diagram of a base station 300 according toan embodiment of the present invention. As shown in FIG. 6, the basestation 300 includes:

a determining module 310, configured to determine, according to carrierswitching capability information of user equipment UE, a carrierswitching policy according to which the UE performs carrier switching;and

a sending module 320, configured to send carrier switching indicationinformation to the UE, where the carrier switching indicationinformation is used for indicating the carrier switching policydetermined by the determining module 310, so that the UE performscarrier switching according to the carrier switching policy.

Therefore, in the base station according to this embodiment of thepresent invention, UE having no carrier capability is enabled todynamically perform switching between at least two carriers, so thatquality of service of a service of the UE can be improved, userexperience can be improved, and system performance can be improved.

Optionally, the determining module 310 is specifically configured todetermine, according to the carrier switching capability information ofthe UE and current network status information, the carrier switchingpolicy according to which the UE performs carrier switching.

Optionally, as another embodiment, the carrier switching policydetermined by the determining module 310 includes completing carrierswitching from a current downlink carrier to a target downlink carrierin an M1^(th) subframe after a current subframe in which the carrierswitching indication information is sent to the UE, where M1 is aninteger greater than or equal to 1.

Optionally, as another embodiment, the carrier switching policydetermined by the determining module 310 includes completing carrierswitching from a current uplink carrier to a target uplink carrier in anM2^(th) subframe after the current subframe in which the carrierswitching indication information is sent to the UE, where M2 is aninteger greater than or equal to 1.

Optionally, as another embodiment, when the current downlink carrier andthe current uplink carrier in the carrier switching policy aresystem-associated carriers, and the target downlink carrier and thetarget uplink carrier to which the UE performs carrier switching aresystem-associated carriers, a time needed to switch the UE from thecurrent downlink carrier to the target downlink carrier is equal to atime needed to switch the UE from the current uplink carrier to thetarget uplink carrier.

Optionally, as another embodiment, the sending module 320 isspecifically configured to send downlink control information DCIcarrying the carrier switching indication information, where the DCI isfurther used for instructing the UE to receive downlink data on thecurrent downlink carrier; or

the sending module 320 is specifically configured to send DCI carryingthe carrier switching indication information, where the DCI is furtherused for instructing the UE to send uplink data on the current uplinkcarrier or on the target uplink carrier to which carrier switching isperformed; or

the sending module 320 is specifically configured to send DCI carryingthe carrier switching indication information, where the DCI is used forinstructing the UE to perform carrier switching according to the carrierswitching policy.

Optionally, as another embodiment, a carrier indicator field CIFincluded in the DCI sent by the sending module 320 is used for carryingthe carrier switching indication information.

Optionally, as another embodiment, the DCI sent by the sending module320 is scrambled by using a cell identifier corresponding to a targetcarrier, so as to instruct the UE to switch from a current carrier tothe target carrier; or

the DCI sent by the sending module 320 instructs the UE to feed backchannel state information of the target downlink carrier, so as toinstruct the UE to switch from the current downlink carrier to thetarget downlink carrier.

Optionally, as another embodiment, the determining module 310 is furtherconfigured to: before the carrier switching policy according to whichthe UE performs carrier switching is determined according to the carrierswitching capability information of the UE, determine aprimary-component-carrier subframe pattern of the UE, where theprimary-component-carrier subframe pattern is used for instructing theUE to communicate with the base station in a first subframe by using aprimary component carrier of the UE; and determine the carrier switchingpolicy of the UE according to the carrier switching capabilityinformation of the UE and the primary-component-carrier subframepattern.

Optionally, as another embodiment, the carrier switching policydetermined by the determining module 310 includes carrier subframepatterns of at least two carriers, a carrier subframe pattern of eachcarrier of the at least two carriers is separately used for indicating areserved subframe in which the UE communicates with a base station byusing the carrier, and the carrier subframe patterns of the carriers arenot completely overlapped.

Optionally, as another embodiment, a first subframe ratio in the atleast two carriers is a reciprocal of a second subframe ratio, the firstsubframe ratio is a ratio between a quantity of reserved subframes of afirst uplink carrier and a quantity of reserved subframes of a firstdownlink carrier, where the first uplink carrier and the first downlinkcarrier of the at least two carriers are system-associated, and arelative relationship between a location of a reserved subframe of thefirst uplink carrier and a location of a reserved subframe of the firstdownlink carrier satisfies a preset first TDD ratio configuration, wherethe second subframe ratio is a ratio between a quantity of reservedsubframes of a second uplink carrier and a quantity of reservedsubframes of a second downlink carrier, where the second uplink carrierand the second downlink carrier of the at least two carriers aresystem-associated; or

a ratio between subframes of a carrier subframe pattern of a thirddownlink carrier and subframes of a carrier subframe pattern of a fourthdownlink carrier of the at least two carriers is a first TDDconfiguration of seven preset time division multiplexing TDDconfigurations, where the carrier subframe pattern of the third downlinkcarrier corresponds to downlink and special subframes of the first TDDconfiguration, and the carrier subframe pattern of the fourth downlinkcarrier corresponds to an uplink subframe of the first TDDconfiguration.

Optionally, as another embodiment, the base station 300 furtherincludes:

a receiving module 330, configured to: before the determining module 310determines, according to the carrier switching capability information ofthe UE, the carrier switching policy according to which the UE performscarrier switching, receive the carrier switching capability informationof the UE that is sent by the UE.

Optionally, as another embodiment, the carrier switching capabilityinformation of the UE includes at least one piece of the followinginformation: information about a quantity of carriers supported by theUE, information about a carrier frequency band supported by the UE andinformation about a carrier switching type supported by the UE.

Optionally, as another embodiment, the sending module 320 is furtherconfigured to: before the determining module 310 determines, accordingto the carrier switching capability information of the UE, the carrierswitching policy according to which the UE performs carrier switching,send first indication information to the UE, where the first indicationinformation is used for indicating a candidate carrier set according towhich the UE performs carrier switching and/or a switching time delayfor which the UE performs carrier switching.

The base station 300 according to this embodiment of the presentinvention may correspond to a base station in a carrier switching methodaccording to an embodiment of the present invention, and the foregoingand other operations and/or functions of modules in the base station 300are separately used for implementing corresponding processes of methodsin FIG. 1 to FIG. 4, which are not described herein again for purpose ofconciseness.

Therefore, in the base station according to this embodiment of thepresent invention, UE having no carrier capability is enabled todynamically perform switching between at least two carriers, so thatquality of service of a service of the UE can be improved, system loadcan be balanced, user experience can be improved and system performancecan be improved.

FIG. 7 is a schematic block diagram of user equipment UE 400 accordingto an embodiment of the present invention. As shown in FIG. 7, the UE400 includes:

a receiving module 410, configured to receive carrier switchingindication information sent by a base station, where the carrierswitching indication information is used for indicating a carrierswitching policy according to which the user equipment UE performscarrier switching; and

a carrier switching module 420, configured to perform carrier switchingaccording to the carrier switching policy indicated in the carrierswitching indication information received by the receiving module 410.

Therefore, in the user equipment according to this embodiment of thepresent invention, the UE having no carrier capability is enabled todynamically perform switching between at least two carriers, so thatquality of service of a service of the UE can be improved, userexperience can be improved, and system performance can be improved.

Optionally, the carrier switching policy includes completing carrierswitching from a current downlink carrier to a target downlink carrierin an M1^(th) subframe after a current subframe in which the carrierswitching indication information sent by the base station is received,where M1 is an integer greater than or equal to 1.

Optionally, as another embodiment, the carrier switching policy includescompleting carrier switching from a current uplink carrier to a targetuplink carrier in an M2^(th) subframe after the current subframe inwhich the carrier switching indication information sent by the basestation is received, where M2 is an integer greater than or equal to 1.

Optionally, as another embodiment, when the current downlink carrier andthe current uplink carrier in the carrier switching policy aresystem-associated carriers, and the target downlink carrier and thetarget uplink carrier to which the UE performs carrier switching aresystem-associated carriers, a time needed to switch the UE from thecurrent downlink carrier to the target downlink carrier is equal to atime needed to switch the UE from the current uplink carrier to thetarget uplink carrier.

Optionally, as another embodiment, the carrier switching indicationinformation received by the receiving module 410 is carried in downlinkcontrol information DCI, where the DCI is further used for instructingthe UE to receive downlink data on the current downlink carrier; or

the carrier switching indication information received by the receivingmodule 410 is carried in DCI, where the DCI is further used forinstructing the UE to send uplink data on the current uplink carrier oron the target uplink carrier to which carrier switching is performed; or

the carrier switching indication information received by the receivingmodule 410 is carried in DCI, where the DCI is used for instructing theUE to perform carrier switching according to the carrier switchingpolicy and is not used for data scheduling.

Optionally, as another implementation, a carrier indicator field CIFincluded in the DCI is used for carrying the carrier switchingindication information.

Optionally, as another embodiment, the DCI is scrambled by using a cellidentifier corresponding to a target carrier, so as to instruct the UEto switch from a current carrier to the target carrier; or

the DCI instructs the UE to feed back channel state information of thetarget downlink carrier, so as to instruct the UE to switch from thecurrent downlink carrier to the target downlink carrier.

Optionally, as another embodiment, the UE 400 further includes:

a determining module 430, configured to: before the carrier switchingmodule 420 performs carrier switching according to the carrier switchingpolicy, determine a primary-component-carrier subframe pattern of theUE, where the primary-component-carrier subframe pattern is used forinstructing the UE to communicate with the base station in a firstsubframe by using a primary component carrier of the UE; and

correspondingly, the carrier switching module 420 is specificallyconfigured to perform carrier switching according to the carrierswitching policy received by the receiving module 410 and theprimary-component-carrier subframe pattern determined by the determiningmodule 430.

Optionally, as another embodiment, the carrier switching policy includescarrier subframe patterns of at least two carriers, a carrier subframepattern of each carrier of the at least two carriers is separately usedfor indicating a reserved subframe in which the UE communicates with abase station by using the carrier, and the carrier subframe patterns ofthe carriers are not completely overlapped.

Optionally, as another embodiment, a first subframe ratio in the atleast two carriers is a reciprocal of a second subframe ratio, the firstsubframe ratio is a ratio between a quantity of reserved subframes of afirst uplink carrier and a quantity of reserved subframes of a firstdownlink carrier, where the first uplink carrier and the first downlinkcarrier of the at least two carriers are system-associated, and arelative relationship between a location of a reserved subframe of thefirst uplink carrier and a location of a reserved subframe of the firstdownlink carrier satisfies a preset first TDD ratio configuration, wherethe second subframe ratio is a ratio between a quantity of reservedsubframes of a second uplink carrier and a quantity of reservedsubframes of a second downlink carrier, where the second uplink carrierand the second downlink carrier of the at least two carriers aresystem-associated; or

a ratio between subframes of a carrier subframe pattern of a thirddownlink carrier and subframes of a carrier subframe pattern of a fourthdownlink carrier of the at least two carriers is a first TDDconfiguration of seven preset time division multiplexing TDDconfigurations, where the carrier subframe pattern of the third downlinkcarrier corresponds to downlink and special subframes of the first TDDconfiguration, and the carrier subframe pattern of the fourth downlinkcarrier corresponds to an uplink subframe of the first TDDconfiguration.

Optionally, as another embodiment, the UE 400 further includes:

a sending module 440, configured to: before the receiving module 410receives the carrier switching indication information sent by the basestation, send carrier switching capability information of the UE to thebase station, so that the base station determines the carrier switchingpolicy according to the carrier switching capability information.

Optionally, as another embodiment, the receiving module 410 is furtherconfigured to: before the carrier switching indication information sentby the base station is received, receive first indication informationsent by the base station, where the first indication information is usedfor indicating a candidate carrier set according to which the UEperforms carrier switching and/or a switching time delay for which theUE performs carrier switching.

The user equipment 400 according to this embodiment of the presentinvention may correspond to user equipment in a carrier switching methodaccording to an embodiment of the present invention, and the foregoingand other operations and/or functions of modules in the user equipment400 are separately used for implementing corresponding processes ofmethods in FIG. 5, which are not described herein again for purpose ofconciseness.

Therefore, in the user equipment according to this embodiment of thepresent invention, the UE having no carrier capability is enabled todynamically perform switching between at least two carriers, so thatquality of service of a service of the UE can be improved, system loadcan be balanced, user experience can be improved and system performancecan be improved.

FIG. 8 is a schematic block diagram of a base station 500 according toan embodiment of the present invention. As shown in FIG. 8, the basestation 500 includes a processor 510, a memory 520, a bus system 530 anda transmitter 540. The processor 510, the memory 520 and the transmitter540 are connected by using the bus system 530, the memory 520 isconfigured to store an instruction, and the processor 510 invokes, byusing the bus system 530, the instruction stored in the memory 520.Specifically, the processor 510 is configured to determine, according tocarrier switching capability information of user equipment UE, a carrierswitching policy according to which the UE performs carrier switching;and the transmitter 540 is configured to send carrier switchingindication information to the UE, where the carrier switching indicationinformation is used for indicating the carrier switching policydetermined by the processor 510, so that the UE performs carrierswitching according to the carrier switching policy.

Therefore, in the base station according to this embodiment of thepresent invention, UE having no carrier capability is enabled todynamically perform switching between at least two carriers, so thatquality of service of a service of the UE can be improved, userexperience can be improved, and system performance can be improved.

It should be understood that, in this embodiment of the presentinvention, the processor 510 may be a central processing unit (CPU), andthe processor 510 may be further another general-purpose processor, adigital signal processor (DSP), an application-specific integratedcircuit (ASIC), a field programmable gate array (FPGA) or anotherprogrammable logic device, a discrete gate or a transistor logic device,a discrete hardware assembly or the like. The general-purpose processormay be a microprocessor, or the processor may be any common processor orthe like.

The memory 520 may include a read-only memory and a random accessmemory, and provide an instruction and data to the processor 510. A partof the memory 520 may further include a non-volatile random accessmemory. For example, the memory 520 may further store information of adevice type.

Besides including a data bus, the bus system 530 may further include apower supply bus, a control bus, a state signal bus and the like.However, for purpose of clear description, various buses are all markedas the bus system 530 in the figure.

During implementation, the steps of the foregoing method may beimplemented by using a hardware integrated logic circuit in theprocessor 510 or implemented by using an instruction in a software form.The steps of the method disclosed with reference to the embodiment ofthe present invention may be implemented by means of the execution ofthe hardware processor, or implemented by using a combination ofhardware in the processor and a software module. The software module maybe located in a mature storage medium in the field, such as a randomaccess memory, a flash memory, a read-only memory, a programmableread-only memory, an electrically erasable programmable memory, or aregister. The storage medium is located in the memory 520, and theprocessor 510 reads the information in the memory 520, and completessteps of the foregoing method in combination with hardware of theprocessor 510. To avoid repetition, the details are not described hereinagain.

Optionally, the processor 510 is specifically configured to determine,according to the carrier switching capability information of the UE andcurrent network status information, the carrier switching policyaccording to which the UE performs carrier switching.

Optionally, as another embodiment, the carrier switching policydetermined by the processor 510 includes completing carrier switchingfrom a current downlink carrier to a target downlink carrier in anM1^(th) subframe after a current subframe in which the carrier switchingindication information is sent to the UE, where M1 is an integer greaterthan or equal to 1.

Optionally, as another embodiment, the carrier switching policydetermined by the processor 510 includes completing carrier switchingfrom a current uplink carrier to a target uplink carrier in an M2^(th)subframe after the current subframe in which the carrier switchingindication information is sent to the UE, where M2 is an integer greaterthan or equal to 1.

Optionally, as another embodiment, when the current downlink carrier andthe current uplink carrier in the carrier switching policy aresystem-associated carriers, and the target downlink carrier and thetarget uplink carrier to which the UE performs carrier switching aresystem-associated carriers, a time needed to switch the UE from thecurrent downlink carrier to the target downlink carrier is equal to atime needed to switch the UE from the current uplink carrier to thetarget uplink carrier.

Optionally, as another embodiment, the transmitter 540 is specificallyconfigured to send downlink control information (DCI) carrying thecarrier switching indication information, where the DCI is further usedfor instructing the UE to receive downlink data on the current downlinkcarrier; or

the transmitter 540 is specifically configured to send DCI carrying thecarrier switching indication information, where the DCI is further usedfor instructing the UE to send uplink data on the current uplink carrieror on the target uplink carrier to which carrier switching is performed;or

the transmitter 540 is specifically configured to send DCI carrying thecarrier switching indication information, where the DCI is used forinstructing the UE to perform carrier switching according to the carrierswitching policy and is not used for data scheduling.

Optionally, as another embodiment, a carrier indicator field (CIF)included in the DCI sent by the transmitter 540 is used for carrying thecarrier switching indication information.

Optionally, as another embodiment, the DCI sent by the transmitter 540is scrambled by using a cell identifier corresponding to a targetcarrier, so as to instruct the UE to switch from a current carrier tothe target carrier; or

the DCI sent by the transmitter 540 instructs the UE to feed backchannel state information of the target downlink carrier, so as toinstruct the UE to switch from the current downlink carrier to thetarget downlink carrier.

Optionally, as another embodiment, the processor 510 is furtherconfigured to: before the carrier switching policy according to whichthe UE performs carrier switching is determined according to the carrierswitching capability information of the UE, determine aprimary-component-carrier subframe pattern of the UE, where theprimary-component-carrier subframe pattern is used for instructing theUE to communicate with the base station in a first subframe by using aprimary component carrier of the UE; and determine the carrier switchingpolicy of the UE according to the carrier switching capabilityinformation of the UE and the primary-component-carrier subframepattern.

Optionally, as another embodiment, the carrier switching policydetermined by the processor 510 includes carrier subframe patterns of atleast two carriers, a carrier subframe pattern of each carrier of the atleast two carriers is separately used for indicating a reserved subframein which the UE communicates with a base station by using the carrier,and the carrier subframe patterns of the carriers are not completelyoverlapped.

Optionally, as another embodiment, a first subframe ratio in the atleast two carriers is a reciprocal of a second subframe ratio, the firstsubframe ratio is a ratio between a quantity of reserved subframes of afirst uplink carrier and a quantity of reserved subframes of a firstdownlink carrier, where the first uplink carrier and the first downlinkcarrier of the at least two carriers are system-associated, and arelative relationship between a location of a reserved subframe of thefirst uplink carrier and a location of a reserved subframe of the firstdownlink carrier satisfies a preset first TDD ratio configuration, wherethe second subframe ratio is a ratio between a quantity of reservedsubframes of a second uplink carrier and a quantity of reservedsubframes of a second downlink carrier, where the second uplink carrierand the second downlink carrier of the at least two carriers aresystem-associated; or

a ratio between subframes of a carrier subframe pattern of a thirddownlink carrier and subframes of a carrier subframe pattern of a fourthdownlink carrier of the at least two carriers is a first TDDconfiguration of seven preset time division multiplexing TDDconfigurations, where the carrier subframe pattern of the third downlinkcarrier corresponds to downlink and special subframes of the first TDDconfiguration, and the carrier subframe pattern of the fourth downlinkcarrier corresponds to an uplink subframe of the first TDDconfiguration.

Optionally, as another embodiment, the base station 500 further includesa receiver 550, configured to: before the processor 510 determines,according to the carrier switching capability information of the UE, thecarrier switching policy according to which the UE performs carrierswitching, receive the carrier switching capability information of theUE that is sent by the UE.

Optionally, as another embodiment, the carrier switching capabilityinformation of the UE includes at least one piece of the followinginformation: information about a quantity of carriers supported by theUE, information about a carrier frequency band supported by the UE andinformation about a carrier switching type supported by the UE.

Optionally, as another embodiment, the transmitter 540 is furtherconfigured to: before the processor 510 determines, according to thecarrier switching capability information of the UE, the carrierswitching policy according to which the UE performs carrier switching,send first indication information to the UE, where the first indicationinformation is used for indicating a candidate carrier set according towhich the UE performs carrier switching and/or a switching time delayfor which the UE performs carrier switching.

The base station 500 according to this embodiment of the presentinvention may correspond to a base station in a carrier switching methodaccording to an embodiment of the present invention, and the foregoingand other operations and/or functions of modules in the base station 500are separately used for implementing corresponding processes of methodsin FIG. 1 to FIG. 4, which are not described herein again for purpose ofconciseness.

Therefore, in the base station according to this embodiment of thepresent invention, UE having no carrier capability is enabled todynamically perform switching between at least two carriers, so thatquality of service of a service of the UE can be improved, system loadcan be balanced, user experience can be improved and system performancecan be improved.

FIG. 9 is a schematic block diagram of user equipment UE 600 accordingto an embodiment of the present invention. As shown in FIG. 9, the UE600 includes: a processor 610, a memory 620, a bus system 630 and areceiver 640. The processor 610, the memory 620 and the receiver 640 areconnected by using the bus system 630, the memory 620 is configured tostore an instruction, and the processor 610 invokes, by using the bussystem 630, the instruction stored in the memory 620. Specifically, thereceiver 640 is configured to receive carrier switching indicationinformation sent by a base station, where the carrier switchingindication information is used for indicating a carrier switching policyaccording to which the user equipment UE performs carrier switching; andthe processor 610 is configured to perform carrier switching accordingto the carrier switching policy indicated in the carrier switchingindication information received by the receiver 640.

Therefore, in the user equipment according to this embodiment of thepresent invention, the UE having no carrier capability is enabled todynamically perform switching between at least two carriers, so thatquality of service of a service of the UE can be improved, userexperience can be improved, and system performance can be improved.

It should be understood that, in this embodiment of the presentinvention, the processor 610 may be a central processing unit (CPU), andthe processor 610 may be further another general-purpose processor, adigital signal processor (DSP), an application-specific integratedcircuit (ASIC), a field programmable gate array (FPGA) or anotherprogrammable logic device, a discrete gate or a transistor logic device,a discrete hardware assembly or the like. The general-purpose processormay be a microprocessor, or the processor may be any common processor orthe like.

The memory 620 may include a read-only memory and a random accessmemory, and provide an instruction and data to the processor 610. A partof the memory 620 may further include a non-volatile random accessmemory. For example, the memory 620 may further store information of adevice type.

Besides including a data bus, the bus system 630 may further include apower supply bus, a control bus, a state signal bus and the like.However, for purpose of clear description, various buses are all markedas the bus system 630 in the figure.

During implementation, the steps of the foregoing method may beimplemented by using a hardware integrated logic circuit in theprocessor 610 or implemented by using an instruction in a software form.The steps of the method disclosed with reference to the embodiment ofthe present invention may be implemented by means of the execution ofthe hardware processor, or implemented by using a combination ofhardware in the processor and a software module. The software module maybe located in a mature storage medium in the field, such as a randomaccess memory, a flash memory, a read-only memory, a programmableread-only memory, an electrically erasable programmable memory, or aregister. The storage medium is located in the memory 620, and theprocessor 610 reads the information in the memory 620, and completessteps of the foregoing method in combination with hardware of theprocessor 610. To avoid repetition, the details are not described hereinagain.

Optionally, the carrier switching policy includes completing carrierswitching from a current downlink carrier to a target downlink carrierin an M1^(th) subframe after a current subframe in which the carrierswitching indication information sent by the base station is received,where M1 is an integer greater than or equal to 1.

Optionally, as another embodiment, the carrier switching policy includescompleting carrier switching from a current uplink carrier to a targetuplink carrier in an M2^(th) subframe after the current subframe inwhich the carrier switching indication information sent by the basestation is received, where M2 is an integer greater than or equal to 1.

Optionally, as another embodiment, when the current downlink carrier andthe current uplink carrier in the carrier switching policy aresystem-associated carriers, and the target downlink carrier and thetarget uplink carrier to which the UE performs carrier switching aresystem-associated carriers, a time needed to switch the UE from thecurrent downlink carrier to the target downlink carrier is equal to atime needed to switch the UE from the current uplink carrier to thetarget uplink carrier.

Optionally, as another embodiment, the carrier switching indicationinformation received by the receiver 640 is carried in downlink controlinformation (DCI), where the DCI is further used for instructing the UEto receive downlink data on the current downlink carrier; or

the carrier switching indication information received by the receiver640 is carried in DCI, where the DCI is further used for instructing theUE to send uplink data on the current uplink carrier or on the targetuplink carrier to which carrier switching is performed; or

the carrier switching indication information received by the receiver640 is carried in DCI, where the DCI is used for instructing the UE toperform carrier switching according to the carrier switching policy andis not used for data scheduling.

Optionally, as another implementation, a carrier indicator field (CIF)included in the DCI is used for carrying the carrier switchingindication information.

Optionally, as another embodiment, the DCI is scrambled by using a cellidentifier corresponding to a target carrier, so as to instruct the UEto switch from a current carrier to the target carrier; or

the DCI instructs the UE to feed back channel state information of thetarget downlink carrier, so as to instruct the UE to switch from thecurrent downlink carrier to the target downlink carrier.

Optionally, as another embodiment, the processor 610 is furtherconfigured to: before carrier switching is performed according to thecarrier switching policy, determine a primary-component-carrier subframepattern of the UE, where the primary-component-carrier subframe patternis used for instructing the UE to communicate with the base station in afirst subframe by using a primary component carrier of the UE; andperform carrier switching according to the carrier switching policyreceived by the receiver 640 and the primary-component-carrier subframepattern.

Optionally, as another embodiment, the carrier switching policy includescarrier subframe patterns of at least two carriers, a carrier subframepattern of each carrier of the at least two carriers is separately usedfor indicating a reserved subframe in which the UE communicates with abase station by using the carrier, and the carrier subframe patterns ofthe carriers are not completely overlapped.

Optionally, as another embodiment, a first subframe ratio in the atleast two carriers is a reciprocal of a second subframe ratio, the firstsubframe ratio is a ratio between a quantity of reserved subframes of afirst uplink carrier and a quantity of reserved subframes of a firstdownlink carrier, where the first uplink carrier and the first downlinkcarrier of the at least two carriers are system-associated, and arelative relationship between a location of a reserved subframe of thefirst uplink carrier and a location of a reserved subframe of the firstdownlink carrier satisfies a preset first TDD ratio configuration, wherethe second subframe ratio is a ratio between a quantity of reservedsubframes of a second uplink carrier and a quantity of reservedsubframes of a second downlink carrier, where the second uplink carrierand the second downlink carrier of the at least two carriers aresystem-associated; or

a ratio between subframes of a carrier subframe pattern of a thirddownlink carrier and subframes of a carrier subframe pattern of a fourthdownlink carrier of the at least two carriers is a first TDDconfiguration of seven preset time division multiplexing TDDconfigurations, where the carrier subframe pattern of the third downlinkcarrier corresponds to downlink and special subframes of the first TDDconfiguration, and the carrier subframe pattern of the fourth downlinkcarrier corresponds to an uplink subframe of the first TDDconfiguration.

Optionally, as another embodiment, the UE 600 further includes:

a transmitter 650, configured to: before the receiver 640 receives thecarrier switching indication information sent by the base station, sendcarrier switching capability information of the UE to the base station,so that the base station determines the carrier switching policyaccording to the carrier switching capability information.

Optionally, as another embodiment, the receiver 640 is furtherconfigured to: before the carrier switching indication information sentby the base station is received, receive first indication informationsent by the base station, where the first indication information is usedfor indicating a candidate carrier set according to which the UEperforms carrier switching and/or a switching time delay for which theUE performs carrier switching.

The user equipment 600 according to this embodiment of the presentinvention may correspond to user equipment in a carrier switching methodaccording to an embodiment of the present invention, and the foregoingand other operations and/or functions of modules in the user equipment600 are separately used for implementing corresponding processes ofmethods in FIG. 5, which are not described herein again for purpose ofconciseness.

Therefore, in the user equipment according to this embodiment of thepresent invention, the UE having no carrier capability is enabled todynamically perform switching between at least two carriers, so thatquality of service of a service of the UE can be improved, system loadcan be balanced, user experience can be improved and system performancecan be improved.

It should be understood that, the term “and/or” in this embodiment ofthe present invention describes only an association relationship fordescribing associated objects and represents that three relationshipsmay exist. For example, A and/or B may represent the following threecases: Only A exists, both A and B exist, and only B exists. Inaddition, the character “/” in this specification generally indicates an“or” relationship between the associated objects.

A person of ordinary skill in the art may be aware that, in combinationwith the examples described in the embodiments disclosed in thisspecification, method steps and units may be implemented by electronichardware, computer software, or a combination thereof. To clearlydescribe the interchangeability between the hardware and the software,the foregoing has generally described steps and compositions of eachembodiment according to functions. Whether the functions are performedby hardware or software depends on particular applications and designconstraint conditions of the technical solutions. A person of ordinaryskill in the art may use different methods to implement the describedfunctions for each particular application, but it should not beconsidered that the implementation goes beyond the scope of the presentinvention.

It may be clearly understood by a person skilled in the art that, forthe purpose of convenient and brief description, for a detailedoperating process of the foregoing system, apparatus, and unit,reference may be made to a corresponding process in the foregoing methodembodiments, and details are not described herein again.

In the several embodiments provided in the present application, itshould be understood that the disclosed system, apparatus, and methodmay be implemented in other manners. For example, the describedapparatus embodiment is merely exemplary. For example, the unit divisionis merely logical function division and may be other division in actualimplementation. For example, a plurality of units or components may becombined or integrated into another system, or some features may beignored or not performed. In addition, the displayed or discussed mutualcouplings or direct couplings or communication connections may beimplemented by using some interfaces. The indirect couplings orcommunication connections between the apparatuses or units may beimplemented in electronic, mechanical, or other forms.

The units described as separate parts may or may not be physicallyseparate, and parts displayed as units may or may not be physical units,may be located in one position, or may be distributed on a plurality ofnetwork units. Some or all of the units may be selected according toactual needs to achieve the objectives of the solutions of theembodiments of the present invention.

In addition, functional units in the embodiments of the presentinvention may be integrated into one processing unit, or each of theunits may exist alone physically, or two or more units are integratedinto one unit. The integrated unit may be implemented in a form ofhardware, or may be implemented in a form of a software functional unit.

When the integrated unit is implemented in the form of a softwarefunctional unit and sold or used as an independent product, theintegrated unit may be stored in a computer-readable storage medium.Based on such an understanding, the technical solutions of the presentinvention essentially, or the part contributing to the prior art, or allor a part of the technical solutions may be implemented in the form of asoftware product. The software product is stored in a storage medium andincludes several instructions for instructing a computer device (whichmay be a personal computer, a server, or a network device) to performall or some of the steps of the methods described in the embodiments ofthe present invention. The foregoing storage medium includes: any mediumthat can store program code, such as a USB flash drive, a removable harddisk, a read-only memory (ROM), a random access memory (RAM), a magneticdisk, or an optical disc.

The foregoing descriptions are merely specific embodiments of thepresent invention, but are not intended to limit the protection scope ofthe present invention. Any modification or replacement readily figuredout by a person skilled in the art within the technical scope disclosedin the present invention shall fall within the protection scope of thepresent invention. Therefore, the protection scope of the presentinvention shall be subject to the protection scope of the claims.

What is claimed is:
 1. A carrier switching method, comprising:determining, by a base station, according to carrier switchingcapability information of user equipment (UE), a carrier switchingpolicy according to which the UE performs carrier switching; andsending, by the base station, carrier switching indication informationto the UE, wherein the carrier switching indication information iscarried in downlink control information (DCI) to indicate the carrierswitching policy and to enable the UE to perform carrier switchingbetween at least two carries according to the carrier switching policy.2. The carrier switching method according to claim 1, wherein thecarrier switching policy comprises: completing carrier switching from acurrent downlink carrier to a target downlink carrier in an M1thsubframe after a current subframe in which the carrier switchingindication information is sent to the UE, wherein M1 is an integergreater than or equal to 1; or completing carrier switching from acurrent uplink carrier to a target uplink carrier in an M2th subframeafter the current subframe in which the carrier switching indicationinformation is sent to the UE, wherein M2 is an integer greater than orequal to
 1. 3. The carrier switching method according to claim 1,wherein the DCI comprises information for instructing the UE to: receivedownlink data on the current downlink carrier; or send uplink data onthe current uplink carrier or on the target uplink carrier to whichcarrier switching is performed; or perform carrier switching accordingto the carrier switching policy and is not used for data scheduling. 4.The carrier switching method according to claim 1, wherein a carrierindicator field (CIF) comprised in the DCI is used for carrying thecarrier switching indication information.
 5. The carrier switchingmethod according to claim 1, wherein: the DCI is scrambled by using acell identifier corresponding to a target carrier for instructing the UEto switch from a current carrier to the target carrier; or the DCIinstructs the UE to feed back channel state information of the targetdownlink carrier, so as to instruct the UE to switch from the currentdownlink carrier to the target downlink carrier.
 6. The carrierswitching method according to claim 1, wherein before determining,according to carrier switching capability information of UE, a carrierswitching policy according to which the UE performs carrier switching,the method further comprises: receiving the carrier switching capabilityinformation of the UE from the UE.
 7. The carrier switching methodaccording to claim 1, wherein the carrier switching capabilityinformation of the UE comprises at least one piece of the followinginformation: information about a quantity of carriers supported by theUE, information about a carrier frequency band supported by the UE, andinformation about a carrier switching type supported by the UE.
 8. Thecarrier switching method according to claim 1, wherein beforedetermining, according to carrier switching capability information ofUE, a carrier switching policy according to which the UE performscarrier switching, the method further comprises: sending firstindication information to the UE for indicating a candidate carrier setaccording to which the UE performs carrier switching and/or a switchingtime delay for which the UE performs carrier switching.
 9. A carrierswitching method, comprising: receiving, by a user equipment (UE),carrier switching indication information from a base station, whereinthe carrier switching indication information is carried in downlinkcontrol information (DCI) for indicating a carrier switching policyaccording to which the UE performs carrier switching between at leasttwo carries; and performing, by the UE, carrier switching according tothe carrier switching policy indicated in the carrier switchingindication information.
 10. The carrier switching method according toclaim 9, wherein the carrier switching policy comprises: completingcarrier switching from a current downlink carrier to a target downlinkcarrier in an M1th subframe after a current subframe in which thecarrier switching indication information from the base station isreceived, wherein M1 is an integer greater than or equal to 1; orcompleting carrier switching from a current uplink carrier to a targetuplink carrier in an M2th subframe after the current subframe in whichthe carrier switching indication information from the base station isreceived, wherein M2 is an integer greater than or equal to
 1. 11. Thecarrier switching method according to claim 9, wherein the DCI comprisesinformation for instructing the UE to: receive downlink data on thecurrent downlink carrier; or send uplink data on the current uplinkcarrier or on the target uplink carrier to which carrier switching isperformed; or perform carrier switching according to the carrierswitching policy and is not used for data scheduling.
 12. The carrierswitching method according to claim 9, wherein a carrier indicator field(CIF) comprised in the DCI is used for carrying the carrier switchingindication information.
 13. The carrier switching method according toclaim 9, wherein: the DCI is scrambled by using a cell identifiercorresponding to a target carrier for instructing the UE to switch froma current carrier to the target carrier; or the DCI instructs the UE tofeed back channel state information of the target downlink carrier, soas to instruct the UE to switch from the current downlink carrier to thetarget downlink carrier.
 14. The carrier switching method according toclaim 9, wherein before receiving carrier switching indicationinformation from a base station, the method further comprises: sendingcarrier switching capability information of the UE to the base stationfor determining the carrier switching policy according to the carrierswitching capability information.
 15. The carrier switching methodaccording to claim 9, wherein the carrier switching capabilityinformation of the UE comprises at least one piece of the followinginformation: information about a quantity of carriers supported by theUE, information about a carrier frequency band supported by the UE, andinformation about a carrier switching type supported by the UE.
 16. Thecarrier switching method according to claim 9, wherein before receivingcarrier switching indication information from a base station, the methodfurther comprises: receiving first indication information from the basestation for indicating a candidate carrier set according to which the UEperforms carrier switching and/or a switching time delay for which theUE performs carrier switching.
 17. A base station, comprising: aprocessor, configured to determine, according to carrier switchingcapability information of user equipment (UE), a carrier switchingpolicy according to which the UE performs carrier switching; and atransmitter, configured to send carrier switching indication informationto the UE carried in downlink control information (DCI) to indicate thecarrier switching policy determined by the processor and to enable theUE to perform carrier switching between at least two carries accordingto the carrier switching policy.
 18. The base station according to claim17, wherein the carrier switching policy determined by the processorcomprises: completing carrier switching from a current downlink carrierto a target downlink carrier in an M1th subframe after a currentsubframe in which the carrier switching indication information is sentto the UE, wherein M1 is an integer greater than or equal to 1; orcompleting carrier switching from a current uplink carrier to a targetuplink carrier in an M2th subframe after the current subframe in whichthe carrier switching indication information is sent to the UE, whereinM2 is an integer greater than or equal to
 1. 19. The base stationaccording to claim 17, wherein the DCI comprises information forinstructing the UE to: receive downlink data on the current downlinkcarrier; or send uplink data on the current uplink carrier or on thetarget uplink carrier to which carrier switching is performed; orperform carrier switching according to the carrier switching policy andis not used for data scheduling.
 20. The base station according to claim17, wherein a carrier indicator field (CIF) comprised in the DCI fromthe transmitter is used for carrying the carrier switching indicationinformation.